One-cylinder two-piston after-top-dead-center before-45-degree-angle fire blast working internal combustion engine

Disclosed is a one-cylinder two-piston after-top-dead-center before-45-degree-angle fire blast working internal combustion engine which is an energy-saving internal combustion engine capable of enabling a power piston to acquire highest fire blast pressure to do work after a top dead center and when rotating angle of a crankshaft is larger than 43-degree optimal output angle. Two different pistons including the power piston (48) and a rectangular secondary compression coordination piston (16) are designed and assembled in one cylinder. The power piston does not inject oil or ignite before completing discharging, entering and pressing three strokes and entering a working stroke top dead center; after the power piston (48) descends to the top dead center in the working stroke and when the rotating angle of the crankshaft is larger than the 43-degree optimal output shaft, the rectangular piston (16) also synchronously completes own secondary compression coordination work through mechanical program-controlled ope