Objective To establish an in vitro skin sensitization test, human cell line activation test ( h-CLAT), based on THP-1 cell line (a human acute monocytic leukemia cell line), and to assess the sensitizing potency of plant raw materials of chemical and cosmetic products by this in vitro skin sensitization test. Method THP-1 cells were cultured in vitro and exposed to 11 reference skin sensitization chemicals and 9 samples, by monitoring the cell viability, cell surface marker CD54/CD86 and relative fluorescence intensity of cells surface after the cells was exposures to the substances, and to discover whether there is a positive reaction. At the same time, Buehler test was used to validate the results of samples tested by h-CLAT. Results 11 reference chemicals were distinguished correctly by h-CLAT. Among the 9 samples tested, 7 samples were recognized as negative sensitizer and 2 plant extracted substances were identified as suspicious skin sensitizer. The qualitative classification of the 9 samples by h-CLAT test was consistent with the results obtained by animal test. Conclusions The h-CLAT-in vitro test can be used to replace some animal tests for the prediction of soluble skin sensitizing substances.