A two-phase filtering reconfigurable optical physical unclonable function is proposed using the optical speckle. Firstly, the random and unclonable optical speckles are produced by random deviation of the spatial Brownian motion, optical interference and diffraction. Then, the mode selection and two-phase filtering methods are used to realize the reconfigurable function and reduce systematic error. Finally, the optical speckle image is acquired with the help of charge-coupled device system. After binarization and von Neumann processing, the binary data of the physical unclonable function is got with characteristics of randomness, robustness, and reconfigurable. 10 sample optical physical unclonable functions, which each sample can produce 512-bit binary data, are fabricated and tested. The experimental results show that the proposed physical unclonable function passes all National Institute of Standards and Technology randomness tests, the randomness of the physical unclonable function output is 99%, and the two-phase filter method reduces the system error about 3%.