Characteristics extraction method of rice panicle images was proposed to solve the traditional measurement problems, such as inefficiency, worse repeatability, obtaining multi-parameters difficultly. There was significant correlation between primary branch length and spikelet number obtaining by manual measurement. Consequently, rice panicle was spread out and images were captured. Image characteristics were extracted using some image processing operations, including area, primary branch length, and panicle skeleton. Experimental result showed that the correlation coefficients were up to 0.90 between image characteristics and spikelet number, and the average predicting error of the model was 7.90%. Consequently, characteristics extraction method of rice panicle images was effective and feasible. The area and primary branch length can be perfect expression and substitute for spikelet number.