To　improve　the　X-C　direct-drive　platform　curve　machining　contour　accuracy,　the　coupling　control　system　of　double　axis　was　introduced.　Based　on　X-C　tangential　point　linkage　grinding　principle,　the　calculation　model　for　X,　C　axis　tracking　error　coupling　form　contour　error　was　proposed,　and　X-C　direct　drive　coupling　control　system　was　designed.　To　weaken　the　influence　of　factors　such　as　contour　trajectory,　processing　speed　change,　load　change　and　two-axis　control　parameters　on　curve　contour　accuracy　in　process　of　curve　contour　X-C　grinding,　the　nonlinear　PID　control　strategy　was　designed　to　compensate　the　contour　error.　The　X-C　direct-drive　platform　simulation　model　was　established　based　on　linear　motor　and　torque　motor.　By　choosing　the　cam　processing　as　the　example,　the　simulation　results　showed　that　the　nonlinear　coupling　controller　could　improve　the　machining　contour　accuracy　of　X-C　direct-drive　platform.