The invention discloses a printer scraper and an ink return knife adjusting device. A height detection circuit detects the heights of the scraper and the ink return knife to a printing plate in real time through a laser ranging sensor with the model number of H-PT50, the signals of the heights enters a voltage-controlled oscillator used operational amplifiers AR2 and AR3 as cores to output frequency signals of 0-10 kHz, the frequency signals is sent to a difference value signal processing circuit through a transmission line; the frequency signals and a frequency signal of 0-10 kHz converted bythe height given signal of the scraper and the ink return knife after being subjected to suppression of electromagnetic interference, smoothing and the voltage frequency converter enter a frequency difference circuit with triodes Q1, Q2, Q3 and Q4 as cores, frequency deviations are calculated and converted into 0-10 V voltage, finally the frequency deviations entering a window comparison circuitwith the operational amplifiers AR4 and AR5 as cores and are compared with a threshold value; when the deviation is exceeded, the triode Q5 is switched on and the 0-10 V voltage enters the controller,and the controller controls the height to be automatically adjusted. The device effectively solves the problem that the height of the ink scraping knife and the ink return knife cannot be automatically controlled in the prior art.