The invention provides a membrane pore structure and a porosity testing method based on CLSM (confocal laser scanning microscopy), comprising: preparing a sample, observing the sample, processing data and the other steps. Traditional testing methods include scanning electron microscopy, transmission electron microscopy, mercury intrusion method, nitrogen adsorption method and other methods and have their respective disadvantages; for example, high pressure required in the testing process of the mercury intrusion method may deform membrane structure; sample preparation in the transmission electron microscopy and scanning electron microscopy is high in time consumption and results in big damage to samples. Membrane pore structure and porosity are tested by means of confocal laser scanning microscopy, it is only required to perform single dyeing on a sample under test with fluorescent dye, information in the sample can be acquired without destroying the sample, operating is simple, and little damage is caused to the sample; in addition, sample testing herein has no need for drying, namely, a sample can be tested in an environment similar to a membrane when a liquid separation membrane is under test, and the results are more accurate and reliable.