The analysis results of emissive no uniform (patchy) surface of thermionic cathode are presented. The presence of two kinds of patches had taken info account. The effect of patches contact field on the value of anode current in a diode is considered as electron interception leg patches with the greater work function. In the capacity of the characteristic which determinates this process interception parameter is proposed. The use of a computer simulation of the emitting surface with two kinds of patches and parameter of interception from the experiment makes possible to detect the values of patches work function and fractions of surface with these patches.