The possibilities for running in a city with 16 millions of inhabitants are of course not comparable with what we have e.g. in the Black Forest. Clean air or not paved roads are almost not available ...
Anyway I found four possibilities. Here is a short overview:
1. At the Pearl River resp. on ErSha Dao Island
2. In one of the parks (e.g. TianHe Park with a maximum distance for one round of about 3.3Km)
3. At Bayun Mountain
4. At the campus of one of the many different universities (e.g. in TianHe or in University Town South East of downtown Guangzhou)
Here are some details:
1. Along the Pearl River:
All my long training runs I did along the Pearl River, combining the 7km and 12km loops. The route itself isn't rich in variety, but it offers a beautiful glimpse into the Chinese way of life, especially in the early morning or on weekends. In the evening, the view of the Guangzhou skyline is remarkable. The downside is that it is necessary to cross the bridges, which are often crowded by pedestriants.
Here the 12Km loop starting on ErSha Dao island. Below from left to right: Hayin Bridge, Guangzhou Bridge and Liede Bridge.

2. In one of the parks in Guangzhou (eg. TianHe Park, ZhuJiang Park)
TianHe Park is located about halfway between the location I work and my home in Guangzhou's TianHe district. The 3.3km loop is my standard weekday evening running route. I usually run three laps. Same as along the Pearl River also here it is possible to enjoy observing the "Chinese way of life" in the evening. After dinner, the park fills with walkers, joggers, music listeners, dancers, and so on. And the dense tree cover is especially pleasant in the summer at very often more than 30 degrees Celsius in the evening.

3. At Bayun Mountain
There are also hilly trails to run in Guangzhou. This is a bit of a challenge for me because the starting point is several kilometers away and more time consuming to reach. However, it's a nice change compared to my standard running route along the Pearl River resp. in TianHe Park. And along the way, there's also the opportunity to take a break with a drink and enjoy a beautiful view of Guangzhou.
Here a 12Km route starting at the Bayun Mountain cable car and ending at Guangdong University for Foreign Studies.

4. Around one of the many universities in Guangzhou:
Some of the many universities in Guangzhou are located in downtown Guangzhou. The South China University of Technology for example is located close to the subway station "Wushan" and is surounded by a big park with many trees. When living close to one of these places it's a good option to go running around these universities.
Southeast of Guangzhou in the so called University Town about 10 universities are located. Although not particularly exciting, the vast area is also good for running. This area is also popular with road cyclists. The long loop is about 17 kilometers long. However, there is hardly any shade, so running here during the day in midsummer is definitely not recommended.

 
                                                            