Abstract: It is provided a portable tester for leakage rate of a cylinder of an automobile engine. The portable tester includes a shell; wherein a circuit board and a manifold body are provided in the shell; a throttle hole is provided inside the manifold body, the shell includes a front shell and a rear shell; a display and a control key are provided respectively at an upper end of and at a middle part of the front shell; the circuit board is provided with a decoding drive electrically connected with the display, and a single chip microcomputer unit is provided on the decoding drive and electrically connected with the control key; an air inlet connecter and an air outlet connector are provided at the lower end of the front shell. Two ends of the manifold body are provided with sensors electrically connected with the single chip microcomputer unit.