The present invention relates to an assistant monitor method for vehicle, comprising steps of: projecting a light beam to illuminate objects surrounding a transportation means; receiving the reflected light of the light beam so as to generate an electric image signal accordingly; generating a status signal by detecting and sensing the status of the transportation means; processing the status signal so as to correspondingly generate a control signal; and adjusting the projecting angle of the light beam and the receiving angle to receive the reflected light beam according to the control signal. Moreover, according to the method, the present invention also provides an assistant monitor apparatus of for vehicle to implement the foregoing method. By means of the aforesaid apparatus provided in the present invention, the projecting direction of the light projector and a sensing angle of the image sensor for receiving the reflected light can be controlled to reduce blind spots of a rear mirror of the transportation means while avoiding the whitening effect to be generated on the rear mirror, such that safety of the driver driving the transportation mean along with the ambient vehicles and pedestrians can be ensured.