In order to solve the problem that the border, between dark crescent and bright crescent, is hard to be detected in the pupil images of infrared eccentric photorefraction, a geometrical plane parameter measurement method based on pupil images processing is proposed in this paper. The key technologies are curvelet transform and least-squares fitting. Firstly, we obtained the pupil images by the infrared eccentric photography system. Secondly, curvelet was utilized to reduce the noise from the images, and the rough edges could be located. Thirdly, by least-squares fitting to the edge, we could acquire the geometrical plane parameters of pupil images more accurately. Finally, pupil diopter could be calculated. The experimental results demonstrate the accuracy, stability and validity of the measurement system.