For a general full-Stokes polarimeter(FSP),there are two types of noises,signal-dependent Poisson shot noise and signal-independent Gaussian additive noise,which will degrade the signal-to-noise ratio(SNR)on the measured Stokes parameters.The relation between the immunity to Gaussian noise and the condition of the measurement matrix has been widely studied in the recent literature.Herein,we present a new metrics and use it to achieve optimal configurations with the immunity to both types of noises.Our studies show that,for the Configuration(I)consisting of a variable retarder followed by a fixed polarizer,the four measurement channels composed of a 102° retardance with a pair of azimuths ±72° and a 142° retardance with a pair of azimuths ±35° are found to be immune to these two noises.For the Configuration(Ⅲ)consisting of two variable retarders followed by a fixed polarizer,the four measurement channels composed of two quarter-wave-plate(QWP)with four pairs of azimuths(±70°,±88°)and(±43°,±19°)are found to be one of optimal settings.The tolerances of the retardances or azimuths in the optimized configurations are evaluated for practical manufacture,assembling and alignment.