Systems and methods for voltage compensation based on load conditions in power converters. For example, a system controller for regulating a power converter includes a first controller terminal; a second controller terminal; and a compensation current generator. The compensation current generator is configured to receive an input signal through the first controller terminal. The input signal indicates a first current flowing through a primary winding of a power converter. The compensation current generator is configured to receive a demagnetization signal related to a demagnetization period of the power converter and associated with an auxiliary winding of the power converter. The compensation current generator is configured to generate a compensation current based at least in part on the input signal and the demagnetization signal. The compensation current generator is connected to a resistor. The resistor is configured to generate a compensation voltage based at least in part on the compensation current.