The contents of 21 kinds of PhACs in 8 classes drugs such as sulfanilamide type, macrolide type, carbostyril type, anti-pain and anti-inflammation type, anti-epileptic type and so on in the influent water of Chongqing Jiguanshi Waste Water Treatment Plant, the biggest waste water treatment plant in southwest area of China, were technically detected by solid-phase extraction method, high performance liquid chromatography/tandem mass spectrometry. The consumption quantity of these drugs in Chongqing is calculated by taking the advantage of the amount of PhACs in the influent water of this Plant and by considering pharmacokinetics in human body, for example, the usage of Ofloxacin is well consistent with the practical usage (similarity degree 72.5 percent), however, the reverse-calculation usage of PhACs needs to be further confirmed. Usually, the influent water mass load of the selected antibiotics is similar or a little higher than the reported per capita consumption level in developed countries but the target PhACS of other types are on the contrary of this result.