The invention discloses a testing method for predicting the residual service life of a buried metal water supply pipeline, which relates to a testing method comprising the following steps: (1) inputting testing data of environmental factors affecting the corrosion of the buried metal water supply pipeline and water quality change conditions in the pipeline in different periods of time into a computer; (2) respectively computing the collected data in the computer by a mathematical statistics method, and establishing a nonlinear regression equation in one unknown; (3) computing the weighted value of each factor affecting pipeline corrosion by a grey theory computing method; (4) establishing corrosion rate models (an internal corrosion model and an external corrosion model) of the buried metal water supply pipeline; and (5) according to an electrochemical model of the soil corrosion rate, respectively establishing prediction models for the residual service life of the buried metal water supply pipeline by uniform corrosion, local corrosion and pitting corrosion, and computing the residual service life of the buried metal water supply pipeline by an approximate analytical method. The invention provides a technical reference for carrying out transformation and renovation of pipelines and improving the safety of a water supply system.