Abstract: A rapid approach was described to estimate the chronic toxicity of toxicantsto the Grobiocypris rarus.Tests were initiated .Tests were initiated using +2, Cr+6, Zn+2 and PCP were 20, 2500, 100, 40ug /L and 40, 5000, 200,80ug/L, respectively,when standing crop was used as endpoing.Compared with 7d subchronic test using the same reference toxicants, the results agreed well, whichindicate that short-term methods for estimating the chronic toxicity to freshwater fishmay be shorten from 7d to 5d.