In two-dimensional rectangular array photonic crystal, one parallel line waveguides are formed by removing the middle line silicon pillars. On the right of the line waveguide, a point waveguide has been introduced. It′s coupling properties are investigated by use of finite-difference time-domain (FDTD) method and the splitting ratio of two channels has been counted. The results show that the splitting ratio changes obviously is found when the temperature of the photonic crystal is rising. A new optical power splitter is brought forward based on this research and a wide range of light power ratios, from 11 to 901 can be obtained. This function can be realized by regulating the temperature from 0 ℃ to 200 ℃. Finally a three channels and tunable optical power splitter is designed, which can distribute the power of the light by adjusting the two point defects′ temperature.