In order to evaluate the influence of well site noise on MWD telemetry system more accurately and effectively, this paper develops an efficient noise acquisition system to acquire the drilling site noise, which consists of low-noise coupling transformer, low noise preamplifier and tunable filter, usb6259 acquisition card, computer and other components. Although, most methods can be used to estimate noise statistical characteristics and model based on large samples, the Bootstrap method is a computer method, which only requires very little in the way of modelling or analysis noise. Through electromagnetic noise examples from an operating oil field, located near Northwest of China, we demonstrate the drilling site noise data with different drill rigs and in different drill operations were analyzed based on the Bootstrap method and Welch's method. The trial result shows that (i) the system can work easily for the well-site electromagnetic noise real-time acquisition, signal processing and analysis, display and storage; (ii) the power spectral density of well site noise were strongly dependent on the noise which is generated by the industrial equipment operating and drilling conditions in the well site and (iii) the maximum kurtosis of drilling site noise of Electro-Mechanical Drilling Rig is 7.437, which indicate it is not Gauss distribution, but super-Gauss distribution. The findings of our work can help for better understanding of characteristics of drilling site noise. Furthermore, the Bootstrap method is a powerful tool for analysis and evaluation drilling site noise with low cost, and can solve the problem that the practical drilling process data can not be obtained repeatedly. The results can be used to improve MWD, EM-MWD and LWD system designs and optimization studies.