The invention discloses a three-dimensional grid strain measurement method, which comprises the following steps of: step 1, grid preparation; step 2, sampling and shooting; step 3, picture orientation; step 4, grid node matching; step 5, grid node rebuilding; step 6, grid connection, step 7, grid optimization; and step 8, strain calculation. Through the operation steps, the method can be used for measuring the three-dimensional full field strain information in the metal plate material forming process, and the metal plate material forming performance and the advantages and disadvantages of the mold process design scheme can be evaluated, so the metal plate material forming quality is improved, the manufacture precision is improved, and the production cost is reduced. The three-dimensional grid strain measurement method has the characteristics that the measurement operation is convenient, the automation degree is high, the result is accurate and reliable, the measurement information is rich, the efficiency is high, and in addition, the non-contact measurement is realized.