Thermal estimation device and thermal estimation method

An embodiment of a thermal estimation device including a temperature model generator, a temperature gradient calculator, and a thermal sensing analyzer is disclosed. The temperature model generator generates a temperature model based on an initial power consumption, an initial area and an initial coordination of a circuit module. The temperature gradient calculator substitutes at least one of a testing area, a testing power or a testing coordinate of the circuit module into the temperature model for correspondingly estimating an temperature estimation function. The thermal sensing analyzer differentiates the temperature estimation function. When an absolute value of a differential result of the temperature estimation function resulted from a constant is closest to zero or is zero, outputting the constant as an optimized parameter.