The invention provides a tester dustproof device, and aims at solving the technical problems of the phenomenon of short circuit in the test caused by ash deposit on a test panel due to long time arrangement of a tester. The adopted technical scheme is the tester dustproof device which comprises a test box and dustproof cloth. The periphery of the test box is provided with a circle of guide rail. The cross section of the guide rail presents to be a rectangle of which the middle of the upper surface is provided with an opening. Guide posts are connected at the four corners of the dustproof cloth. The distance between the guide posts is equal to the distance between the four corners of the guide rail. The bottom ends of the guide posts stretch into the guide rail. The position corresponding to the opening of the guide rail is provided with an annular groove. The guide posts can move along the guide rail. When the tester is not used for a long time, the guide posts are moved to the four corners of the guide rail along the guide rail and the dustproof cloth covers the upper part of the test box so that the situation of short circuit caused by ash deposit on the test panel can be avoided; and when the tester requires to be used for testing, the four guide posts are moved to the same side and the test box is exposed so that testing is not influenced. The tester dustproof device is simple in structure and portable, small and low in weight.