this is metaphor,literally means 苏杭 as beautiful as heaven. 苏杭 is a wonderful city in China. This sentence is from the ancient Chinese poet,use to express the beauty of the city.

上有天堂 = up, there is a heaven 下有苏杭 = down, there are 苏杭 cities 苏杭 is 苏州 and 杭州, they're 2 rich and relaxing cities. This phrase means that these 2 cities are as good as heaven.

Ok, it is very clear now! Thanks to you all, i would choose all comments as a best response, but only can choose one :/ , would be the first one.

Paradise in the heaven, Suzhou and Hangzhou on the earth... PS:Suzhou and Hangzhou is two places in China

as there is the a paradise in heaven, there are Suzhou and Hangzhou on earth. It means Suzhou and Hangzhou are as beautiful as the paradise. it is a simile.