According to one aspect of this disclosure, a scanning trigger unit includes a clock signal terminal, a first signal input terminal, a fixed level signal terminal, a first input sub-circuit, an output sub-circuit, a first holding sub-circuit, and a signal output terminal. The first input sub-circuit is connected to the first signal input terminal and a control node, and is configured to provide a first valid signal to the control node; the output sub-circuit is connected to the fixed level signal terminal, the clock signal terminal, and the control node, and is configured to provide a second valid signal to the signal output terminal; and the first holding sub-circuit is connected to the fixed level signal terminal and the signal output terminal, and is configured to hold the second valid signal at the signal output terminal for a predetermined time.