The electric field effect on the 3dnl and 4dnl doubly excited autoionization states of Ca and Sr atoms have been observed using a multisiep laser excitation technique. The Stark spectra show that splittings of the Stark levels are linearly dependent on the applied electric field in the lowfield region of F5. We have observed also that the autoionization resonance broadens with increasing electric field because of field-induced mixing of nearly degenerate 1 substates, which can play important role for increase of dielectronic recombination rate in plasmas.