Aimed at the problem that the localization accuracy of current indoor WiFi positioning method is low a new method of WiFi indoor carrier phase precise location based on Chinese remainder theorem is proposed. According to the characteristics of WiFi signal multifrequency modulation, the proposed algorithm explores the potential auxiliary efficiency of WiFi technology to improve the indoor ranging performance without changing the structure of commercial hardware. The congruence group is constructed by using the carrier phase measurement of multiple frequency points, and solving the group to measure distance based on Chinese Remainder Theorem, thus effectively eliminating the integer ambiguity in the carrier phase ranging. On the basis of analyzing the ranging accuracy and the noise sensitivity, a method is presented reduce noise sensitivity. According to the actual positioning application requirements, the carrier frequency, SNR, and measurement distance are respectively configured to build a simulation system. This method is compared with the existing RSSI and TOA for 100 simulation experiments. The simulation results show that the average ranging accuracy of the proposed method is 88 mm under the condition of 20 dB SNR and 25 m measurement distance. The method is superior to the existing universal WiFi positioning method and is of great value to application in terms of theory and practice.