1.33°。The measurement method was developed for determining contact angle by fitting the unilateral drop profile. The concept of contact angle’s stable interval was put forward, and a numerical experiment method for the optimization of fitting functions and fitting pixel numbers was established. The presented method was compared to the axisymmetric integral method, with contact angle deviation 1.92%. Because the axisymmetric condition was not introduced in this method, it can be used to measure contact angles of non-axisymmetric drops. The contact angles of deionized water on Osmanthus fragrans leaves were measured, and the research results show that: three degree polynomial can be used to fit the drop profile in the pixel number interval and determine contact angle; the contact angles between the principle vein direction and the direction perpendicular to it are obviously different, with the average discrepancy 7.15°, the average discrepancy of left and right contact angles on the same direction is 1.33°.