In order to achieve high-efficiency white LEDs and get the optimal matching between phosphors and LED chips, a novel measurement system and an analytical method for white LED phosphors were proposed. According to the measurement principles of phosphor, monochromatic light was adopted to excite the phosphor, and phosphors’ excitation characteristics were obtained. With each single excitation spectrums, three-dimensional spectral power distribution for a phosphor was achieved, and the spectrum of white LED was acquired by combination with the spectrum of blue LED chip. Luminous efficiencies of the phosphor under different excitation conditions were analyzed. The experimental results show that the measurement system and analytical method are feasible for choosing optimal matching between phosphors and LED chips, and can establish a good foundation for achieving high-efficiency white LED.