We fabricate low threshold current monolithic distributed feedback (DFB) laser with a multi-mode interface (MMI) combiner using butt-joint metal-organic chemical vapor deposition technology with different waveguide structures. Multi-layer mask self-aligned photolithography technology is used to form different waveguides in active and passive regions, respectively. The result shows that the laser threshold current is lower than 10 mA, with 50 dB side-mode suppression ratio.