A UREA-SCR system control method is provided to prevent exhaustion of nitrogen oxide by inducing element injection. A UREA-SCR system control method comprises a first step(S101) for calculating a target element injection quantity; a second step(S103) for measuring element spray pressure and element injection period and calculating actual element injection quantity; a third step monitoring injection difference between actual element injection quantity and target element injection quantity every same fixed time, a fourth stage(S117) which accumulates the difference value for a certain time when the difference is over a certain and sends a warning signal to a driver when the average is over a constant level, and a fifth step which executes the operator element reinfusion inducement plan if difference is not the specified level less than edge.
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