Abstract: The most important characteristics of time reversal (TR) technique are temporal and spatial focusing properties. Based on these, a model of time reversal pulse signal power combining using sparse array is established. The relationship of the statistical characteristics of combining efficiency at the time of maximum amplitude with the phase error and the number of array elements is analyzed. And the influence of phase error and signal type on the combining efficiency is investigated by both theoretical analysis and the numerical simulation. The analysis shows that, in the engineering application, a large number of small power nodes could be used to reduce the effect of phase error. And when the array elements work in the same frequency, polarization and antenna type, the parameter of phase error would affect the combing result. Even though the phase error occurs, the spatial power combining can still be realized with the time reversal technique. The methods and results presented in this paper are useful for the determination of the compromise between the requirements and the possibility.