The conventional method of achieving PID by FPGA consumes a lot of multiplier, adder and memory. FPGA hardware resources can not be reasonably used, and system holds high energy consumption. Research on using direct DA ( DA-Ⅰ) and improved DA ( DA-Ⅱ) algorithm by FPGA to realize the digital PID controller. Compared with the conventional method, DA-Ⅰ algorithm saves many hardware resources；because of using adder, LUT unit and time delay module etc, DA-Ⅱ algorithm can reduce the unit modules further and reduce energy consumption by the application of two stage pipeline technology. Through the comparison of PID controller by the DA-Ⅰ and DA-Ⅱ algorithm, discussed the improved PID controller performance about the hardware resource, processing speed, complexity and energy consumption etc.