To reduce the computational complexity, a novel method of standard Hough transform (SHT), named probabilistic convergent Hough transform (PCHT), is proposed in this paper. PCHT avoids unnecessary cost of SHT in computation by intermittently detecting several points of a line through fast convergence and in memory by using a one-dimensional accumulator. Considering the inevitable error initiated by PCHT, Sensitivity of detection method is introduced to limit the error rate of detecting a fake line within the tolerable range. Experiment is done in various circumstances. Results and comparison between several line detections and PCHT are shown next, and further discussion is given in the final.