Abstract: This paper is concerned with the crack arrest in a current-current-carrying infinite thin plate. A stepped ascending current perpendicular to the crack surface is switched on The electromagnetic field and the temperature field around the tips of a crack of finite length are studied, and the expression of the temperature at the crack tips is obtained. It is shown that the crack tips will melt and welded joints ton be formed if the magnitude of the stepped ascending current and its ascending times are adjusted properly. As a result the propogation of crack can be arrested.