Asymmetric vertical cracks in process of pressure was studied. Based on principle of seepage mechanics, well-test mathematical model, which is asymmetric finite-conductivity vertical fracture with three different outer boundary conditions, was established according to point source function and Green function. Typical curves were obtained with Laplace integral transformation and Stehfest numerical inversion. It shows that typical curve is divided into four flow stages, stage of wellbore storage,1/4-slope bilinear flow, 1/2-slope linear flow and 0.5-value horizontal line radial flow. Asymmetric factors affect mainly end time of bilinear flow stage. The greater the asymmetry factor is, the sooner the bilinear flow stage ends is. The greater the conductivity capability of fracture is, the more unobvious characteristic of pressure derivative curve of bilinear flow stage are. The bigger asymmetric factor is,the more uneven rate distribution of asymmetric fracture is. The model provides theoretical basis for well test analysis of asymmetric finite-conductivity vertical fracture.