A method, which can extract the particle size information with a resolution beyond λ/NA, was proposed. This was achieved by applying Fourier ptychographic(FP) ideas to the present problem. In a typical FP imaging platform, a 2D LED array was used as light sources for angle-varied illuminations, a series of low-resolution images were taken by a full sequential scan of the array of LEDs, and the data were then combined to produce a high-resolution image. Here, the particle size information was extracted by turning on each single LED on a circle, whose radius was chosen according to an expression for the resolution limit. The simulated results show that the proposed method can reduce the total number of images without loss of reliability in the results, and the total number of images can be further reduced by optimizing the aperture overlapping rate.