An optical phased array, a method for reducing a phase error thereof, a LiDAR, and an intelligent apparatus are provided. The optical phased array includes an optical signal output unit, a waveguide unit, and an antenna transmitting unit. The optical signal output unit is configured to output M optical signals. The waveguide unit includes M waveguide pipes, each waveguide pipe includes at least one connection waveguide, and each of the at least one connection waveguide includes an input mode converter, a wide waveguide, and an output mode converter that are connected in sequence. The antenna transmitting unit is configured to transmit M optical signals outputted from the waveguide unit.