Static contact angle of polypropylene hollow fiber membrane had been measured by tangent fitting method. The effects such as droplet size, equilibrium time, environmental temperature and humidity on membrane contact angle were studied. According to relative standard deviation (RSD) of membrane contact angle, the optimal testing parameters were determined. Based on above results, atomic force microscopy was used to characterize membrane surface morphology. Through comparison the angle results of commercial membrane and as-spun fiber, the relevance between membrane roughness and membrane hydrophobic was analyzed as well. The results showed that in order to improve accuracy of testing method, the influence of droplet gravity was avoided when droplet size was less than 0.1 microliter. Droplet equilibrium time, environmental temperature and humidity were the main factors. Regular micro-porous structure increased membrane surface roughness and formed capillary effect, prevented the droplet spreading and sliding along the fiber axial effectively, so membrane hydrophobic performance was improved significantly. The optimal testing parameters are listed as followed: droplet volume is 0.04ul, the environment temperature is 20℃±2℃, humidity is from 25%RH±4%RH to 65%RH±4%RH, droplet equilibration time is within 15 seconds, RSD of membrane contact angle is less than 5%.