The invention relates to a braking energy recovery value determining method and device and an energy recovery system and method. The braking energy recovery value determining method comprises the steps that during whole vehicle braking, the current pressure value of main cylinder braking liquid and the current rotating speed value of a wheel are acquired; a target braking energy recovery value is determined according to the current pressure value and the current rotating speed value. The braking energy recovery method comprises the steps that during whole vehicle braking, a main cylinder pressure sensor collects the current pressure value of the main cylinder braking liquid, and a wheel rotating speed sensor collects the current rotating speed value of the wheel; an ECU system determines the target brake energy recovery value according to the current pressure value and the current rotating speed value; a motor controller controls a motor according to the target braking energy value and generates power, and electric energy generated by power generation is converted into chemical energy to be stored in a battery. According to the scheme, a stroke sensor and relevant accessories do not need to be additionally arranged, and the accuracy of the energy recovery value is improved.