The invention discloses a TTL signal frequency hopping monitoring method. The method is characterized in that the method comprises the following steps: the frequency doubling operation is performed on a reference clock to obtain a clock I; the frequency division operation is performed on a clock to be monitored to obtain a clock II; a trigger is controlled by the clock I to delay the clock II for N ns and 2N ns separately to obtain a clock III and a clock IV; the xor operation is performed on the clock III and the clock IV to obtain a clock V; counting is performed on the clock I by using a counter; when the clock V is in the high level state, the counter is cleared; when the clock V is in the low level state, the counter start to perform counting; when the rising edge of the clock V reaches, the counting value is latched; the latched counting value is delayed for a period through the clock V to obtain a value II; and comparison is performed between the latched counting value and the value II at each rising edge of the clock V so as to obtain a frequency difference value between the current period and the last period of the clock V, and if the difference value is greater than or equal to a given value, then the signal is hopped for one time. The system and method can be widely used in communications, radar and electronic countermeasure.