The present invention discloses a substrate controllable step morphology pre-
processing method applied to the 
silicon carbide pyrolysis prepared 
graphene. The method comprises the following steps of (1) placing a 
silicon carbide substrate on a pedestal in a 
chemical vapor deposition (CVD) device; (2) setting the pressure in a 
reaction chamber and the 
hydrogen flow, and warming to a beginning 
etching temperature under the 
hydrogen atmosphere; (3) keeping the pressure and the H2 flow to be constant, letting in the small flow 
carbon source auxiliary 
etching while continuously warming to a final 
etching temperature; (4) after warming to the final etching temperature, keeping the pressure, the temperature and the H2 flow to be constant, and improving the 
carbon source flow auxiliary etching slowly in a linear slowly varying manner; (5) closing a valve through which a 
carbon source gets in the 
reaction chamber, carrying out the pure H2 etching; (6) letting in the 
silane auxiliary H2 etchingtowards the 
reaction chamber; (7) cooling to a 
room temperature under the 
hydrogen atmosphere, and taking out a pre-processed 
silicon carbide substrate. The advantages of the present invention are that: a controllable technology window of the pure 
hydrogen etching is expanded, at the same time, the problem that due to the pure 
hydrogen etching, the steps on the surface of the substrate are difficult to control is solved. According to the present invention, a sub-damage layer on the surface of the substrate is removed effectively, the controllable, flat and straight steps having no defects alsocan be formed on the surface of the 
silicon carbide substrate, the dissociation speeds on the steps are consistent, and the supply speeds of the carbon atoms on the step surfaces are same, the growngraphene can be more uniform. The pre-
processing method has a higher popularization value.