A 400G silicon photonic package with a self-aligned fiber includes a printed circuit board (PCB) base, a photonic integrated circuit (PIC) chip, a fiber array unit (FAU), and a distributed feedback (DFB) laser. The PIC chip is mounted on the PCB base; the DFB laser is provided on the PCB base and located outside the PIC chip; the FAU includes a fixed plate, a transmitting-terminal fiber, and a receiving-terminal fiber; V-shaped grooves are formed at a lower side of the fixed plate; the transmitting-terminal fiber and the receiving-terminal fiber are respectively arranged in the V-shaped grooves; the PIC chip is integrated with a photodiode (PD) and a monitor photo detector (MPD); V-shaped guide grooves are further formed in the PIC chip; the transmitting-terminal fiber and the receiving-terminal fiber are clamped between the V-shaped guide groove and the V-shaped groove.