This article reports a new type InGaAsP/InP bistable DH laser (BSDH) formed by proton bombardment with internal modulation on Q factor. The typical bistability exhibiting in L-I curve in these BSDH has been obtained. The current range of bistable operation are 50 mA, 200 mA measured in two samples, respectively. The value can be varied by selecting the device parameters. It is very interesting that the laser light emitted from BSDH operating with various injection currents has a high stable single longitudinal mode. The peak wavelength is 1.2596 μm and the stability on wavelength is about 10-5.Finally, a qualitative discussion is given.