After longperiod use of the imported crawling loaders, the hydraulic systems of the crawling loaders are damaged seriously. The original producer of the crawling loaders does not manufacture such type of loaders any more, therefore the cost of recovery repair is high and the parts for the repair are difficult to purchase. On basis of analysis on the problems occurring during the service of the loaders and the damages of the hydraulic elements, the improper parts of the original hydraulic systems are renovated by adopting standard series of imported parts and Chinamade parts, so as to resume and improve the behavior of the crawling loaders.