The invention proposes an in-chip reset system and reset method for a system-on-chip chip. The system comprises an off-chip key reset circuit, an off-chip crystal oscillation circuit, a chip power-on circuit, a crystal oscillation clock control circuit, a reset signal selection circuit, a reset level pulse generation circuit, an asynchronous reset and synchronous release circuit, a control register, an RC clock circuit, a digital frequency division circuit, a clock selection logic circuit, a delay circuit and a clock switching circuit, wherein except the off-chip key reset circuit and the off-chip crystal oscillation circuit, the rest of circuit modules are all integrated in the system-on-chip (SOC) chip. The in-chip reset system and reset method for the system-on-chip chip have the beneficial technical effects that most circuit modules are integrated in the SOC chip, so that the area is reduced and the cost is lowered; and on the basis of not adding additional circuits, an off-chip key reset mode is effectively combined with an in-chip power-on reset mode, so that the reset system is convenient and easy to use.