A photoacoustic imaging system comprising a coded laser emitting apparatus and a photoacoustic signal receiving apparatus is provided. The coded laser emitting apparatus comprises an encoding unit, a signal generating unit and a laser light source. The encoding unit is used for generating a coded signal. The signal generating unit is used for generating a modulated signal according to the coded signal. The laser light source is used for generating a laser pulse having a specific coded waveform according to the modulated signal. The photoacoustic signal receiving apparatus comprises a photoacoustic signal receiving unit and a decoding unit. The photoacoustic signal receiving unit is used for receiving a photoacoustic signal generated by an object having received the laser pulse and converts the photoacoustic signal into an electrical signal. The decoding unit is used for performing a decoding operation on the aforementioned electrical signal to generate a decoding result, so that a back-end circuit can construct a photoacoustic image according to the decoding result.