Abstract: Analysis of the quantitative relationship between a series of substitutedbenzylidenemalononitriles and the inhibitory action on protein tyrosine Kinases were car-ried out using the Hansch- Fujita method. The results indicate that the presence of two orthree hydroxy groups attached to a phenyl ring, which connects an extended (trans form)conjugated chain, is essential to the inhibition. Compared with the structure of other kindsof inhibitors, a presumable basic structure for inhibiting the enzyme was generated.