The invention discloses a method for monitoring oil-gas pipeline SCADA system data communication on-off. The method comprises the following steps: the step 1, sending a command value and starting a timer by a test system, after receiving the command value and executing negation by a target system, returning; the step 2, comparing whether the returned value within 13 seconds and a sending value are consistent, otherwise, after executing the negation to the sending value by the test system, repeating the step 1; the step 3, adding 1 by a failure counter, after sending the original command value by the test system, repeating the step 1; judging whether the failure count is greater than 2 and the sending value and the returned value are consistent, if the failure count is 1 or 2 and the sending value and the returned value are not consistent, zero-clearing the failure counter; if the failure count is 3, and the sending value and the returned value are consistent, adding 1 to the communication interrupt alarm, determining whether the communication is recovered, if recovered, executing the step 4, otherwise, after adding 1 to the communication interrupt alarm, continuously determining whether the communication is recovered; and the step 4, zero-clearing the communication interrupt alarm count and the failure counter. The method has the beneficial effects of using mutual throwing 0/1 method to realize the oil-gas pipeline SCADA system data communication on-off monitoring, and performing the artificial detection at any time according to the need.