The present invention discloses a high-precision point positioning method and device based on a smartphone. The method of the present invention, which belongs to the technical field of satellite positioning, improves the conventional PPP uncombined positioning model, and only uses original GNSS observation values received by a smartphone to carry out high-precision positioning without GNSS reference stations. The positioning method of the present invention comprises following steps: acquiring original observation values of the smartphone, such as GNSS pseudoranges and carrier phases; after preprocessing the data to decrease part of error influences, generating an uncombined model from the original observation values according to an improved precise point positioning method based on an estimation of double clock biases; determining each satellite observation value weight according to a satellite elevation angle; and carrying out filtering positioning by an improved Kalman filtering method to give a high-precision point positioning result.