Utilizing simultaneously continuous tidal gravity observations from a Burris spring gravimeter in the -848 m deep tunnel and a LCR-ET20 spring gravimeter， surficial and underground gravity noise levels at the deep geophysical experimental field in Huainan were preliminarily analysed. Analysis results show that the underground gravity noise level is lower than the surficial noise level below 1.7 mHz （period about 9.8 min）； especially in the gravimeter senstive frequency band （period over 3 h）， the underground gravity noise level is lower by two orders of magnititude， which fully demonstrates the low noise of ungerground environment at the deep geophysical experimental field in Huainan. Our results further indicate that the -848 m deep tunnel can provide both an ultra quiet environment for deep multi-physical fields observations and a perfect condition for the detection of weak geophysical signals.