The invention provides an aquatic life water quality criteria value derivation method and water quality safety evaluation method. The aquatic life water quality standard value is expressed through the CMC criteria maximal concentration and the CCC criteria continuous concentration; the CMC is acquired through the following formula I: CMC=FAV/2, the FAV is the final acute value, and the CCC equals to the minimal value of the FCV final chronic value, the FPV final plant value, and the FRV final residue value. Through the aquatic life water quality criteria value derivation method, the derived aquatic life water quality criteria value is more scientific and reasonable, and can provide scientific reference for a environmental protection department to formulate water quality standard, evaluate water quality, and perform water quality management.