In response to an earlier request on Danwei for information about snake species found around Beijing, Chinese blogger Hecaitaou kindly provided a brief guide with links to images in the comments section. His guide was in Chinese; below it is translated into English with a few alterations and comments on the English names of the snakes.

The snakes below are apparently common in and around the city of Beijing. Corrections to this guide are of course welcome.

POISONOUS SNAKES

The Banded Red Snake is one of the most widely distributed snakes in China. It is found in all of the suburban districts and counties. In the 1980s, these snakes were still being found in parks and gardens inside the Third Ring Road, even though they are nocturnal and thus difficult to spot. Perhaps because they like to lurk in old houses, all the renovation and rebuilding has caused their numbers to decline. Now they are only found in certain places, and are extinct from many areas.

According to this website, Rhabdophis tigrinus formosanus does not have a common name in English, but the Chinese name translates to Tiger-Striped Neck Groove Snake. It is a mid-sized water snake common all over China. Previously thought not to be poisonous, it was later found that a bite from this snake could cause a wound that does not stop bleeding; if the venom comes into contact with the eye, it can cause the cornea to swell and become bloodshot. This is the most common type of snake in Beijing and there are many of them. They can be found in all the suburban areas and even town and city centers, especially around bodies of water. They do not attack people and there a few reports of people being bitten.

Tiger-Striped Neck Groove Snakes are sometimes found together with Red-backed Ratsnakes, which are also known as Chinese Gartersnakes. Ratsnakes.com has a lot of detailed information about Ratsnakes of the the genus Elaphe.

There are Internet sources that use the English name Short-Tailed Mamushi (link) for this species, others call it call it a Pit Viper (link). The Chinese name 短尾蝮 means Short-Tailed Pit Viper, but the snake is also called 草上飞. Despite the cute sounding name Mamushi, this snake is highly poisonous snake, and very widely distributed, so is one of the most common perpetrators of snake bites injuries in China.

The Short-Tailed Mamushi does not usually attack people, but it's very sluggish, so bites usually happen when people tread on the snakes by mistake. In the Beijing area, they are most commonly found in the mountains west of the city. In recent years there have been frequent reports of snake bites by this snake, a trend that is clearly connected with the expansion of tourist areas and the rising popularity of outdoor sports.

NON POISONOUS SNAKES

The Dione Ratsnake also known as the Steppes Ratsnake is a common non poisonous snake in northern China. It's a hardy snake that can survive periods without food. This snake is common in all suburbs and counties of Beijing.

David's Ratsnake also known as or Pere David's Ratsnake lives in mountainous areas, and river valleys. It is an irritable snake. When angered, it's head forms a triangular shape. It is often mistaken for a poisonous snake. It is a rather rare non poisonous snake. It preys on lizards, rodents and bird eggs.

It is found in rural areas all over northern China, but in small quantities. In the Beijing area is is rarely seen; there have been occasional sightings in Yunmengshan in Huairou, and in the western mountainous aeras of Yanqing and Songshan.

Common in northern eastern and southern China, the Mandarin Ratsnake is rare in the Beijing area, and only found in small numbers in Yunmengshan in Miyun and Huairou, and the Cherry Gorge of the Frangrant Hills in Haidian.

There is more about the wildlife of Beijing (mammals) in this post and in the comments to it: Wild animals of Beijing