A CMOS charge amplifier, due to its very low power consumption and good noise performance, has great interest for analog signal processing in the fields of particle physics, nuclear physics and x-or beta-ray detection. The simulation environment of Eldo (TM) using AMI05 (American Microsystems Inc.) technology provided by Mentor Graphics Corporation is used for noise optimization of a low power CMOS charge amplifier. Using simulation tools we have designed and simulated the output of the charge amplifier and have calculated the power consumption, band width, gain and Equivalent Noise Charge (ENC) of the circuit. We have also studied the factors on which noise of amplifier depends. This has resulted in a noise performance of ENC = 116 electrons at 0 pF detector capacitance with a power consumption of 80 mu W per channel. Due to its very low noise and low power consumption, this kind of new charge amplifier can be widely used in research in the fields of Particle Physics, Nuclear Physics and X-ray detection.