The invention discloses an n-InP-based monolithic integrated optical logic gate. The gate comprises a substrate, an n type diluting waveguide layer, a lower limit layer, a multiple quantum well layer, an upper limit layer, a cover layer, a contact layer, an N type wide bandgap layer, a P type narrow bandgap absorption layer, a P type heavily doped InP electronic barrier layer, a P type heavily doped InGaAs contact layer, an n type metal electrode layer, a silicon nitride or silicon oxide isolating coating, a polymer cladding, a film resistor, a P type microstrip linear metal electrode and a P type electrode board, wherein the n type diluting waveguide layer is manufactured on the substrate; the lower limit layer, the multiple quantum well layer, the upper limit layer, the cover layer and the contact layer are sequentially manufactured on the n type diluting waveguide layer to form an electric absorption modulator structure; the N type wide bandgap layer, the P type narrow bandgap absorption layer, the P type heavily doped InP electronic barrier layer and the P type heavily doped InGaAs contact layer are sequentially manufactured on the n type diluting waveguide layer to form single-row current carrier detector structure; the n type metal electrode layer is manufactured on the n type diluting waveguide layer; the silicon nitride or silicon oxide isolating coating is manufactured on the n type metal electrode layer and covers the side surfaces and surroundings of the electric absorption modulator structure and the single-row current carrier detector structure; the polymer cladding is manufactured on the silicon nitride or silicon oxide isolating coating; the film resistor is manufactured on the polymer cladding; and the P type microstrip linear metal electrode and the P type electrode board are manufactured on the polymer cladding and are connected through the film resistor.