Abstract: For the problem of high fault rate of electric injecting diesel-engine in practical application in drilling and mining machinery, the paper took model OM926LA electric injecting diesel-engine used in model XRHS396 mobile air compressor as an example, introduced control principle of the electric injecting diesel-engine, and pointed out the main fault causes are that basic maintainers are poor in control principle of the electric injecting diesel-engine, diesel oil's quality is bad, the machinery works with long time and mine's environment is threatening. At last, it proposed corresponding measures to solve the problems.