Roughening and pre-roughening processes on InGaAs surface are studied using scanning tunneling microscopy. There are different roughening and pre-roughening processes for InGaAs films at different substrate temperatures and As beam equivalent pressure. Under low temperature and low As beam equivalent pressure, pits is main mechanism in the beginning of InGaAs morphology evolution, with the increase of annealing time, a great number of pits and islands are observed which make the surface rough. Small islands should play a leading role during the InGaAs morphology evolution at high temperature and high As beam equivalent pressure, and the number of islands will increase gradually with the increase of annealing time till it reaches an equilibrium state.