The invention provides an RSSI-based indoor positioning method and system. RSSI signals received by at least three positioning base stations are respectively acquired; Gaussian fitting processing is performed on the acquired RSSI signals, high probability RSSI signals meeting the preset probability threshold in the acquired RSSI signals are reserved and effective RSSI signals are acquired; wavelet transformation is performed on the effective RSSI signals, and the denoised effective RSSI signals are acquired; and indoor positioning is performed by using a Taylor algorithm improved by a positive definite correction matrix according to the denoised effective RSSI signals so as to acquire the positioning result. Data screening and denoising are performed by the Gaussian fitting and wavelet transformation processing in the whole process, the change of the measured RSSI value caused by movement of large equipment and personnel in the indoor scene is considered and the positive definite matrix is introduced to correct the error of estimation offset so as to enhance the positioning accuracy.