Abstract: Shale gas is consisted of free gas, adsorbed gas and dissolved gas. In practical shale gas reservoirs, not only methane is adsorbed, but also other gases such as ethane and propane are parts of the adsorbed gas. Therefore, it is necessary to take multi-component adsorption into consideration when calculating the amount of adsorbed gas. Moreover, some scholars have found that a large amount of shale gas is also dissolved in kerogen, which can not be ignored in the evaluation of shale gas reserves. The paper considers the free gas in fractures, the porosity and volume of adsorbed phase, critical desorption pressure of adsorbed gas and shrinkage distortion of rock matrix caused by the desorption of adsorbed gas, modifies the compressibility of rock, takes multi-component adsorption and dissolved gas into consideration and establishes a new multifactorial material balance equation for shale gas reservoir. The case shows that when considering multi-component adsorption, the calculated free gas reserves basically keeps unchanged, the adsorbed gas reserves increases by 0.308 1×108m3, the total reserves increases by 0.259 5×108m3 (equivalent to 10.97% of the total reserves), and the dissolved gas accounts for 6.58% of the total reserves; considering dissolved gas will lead to a decline in the percentages of reserves of free gas and adsorbed gas, which has a little impact on the total reserves of shale gas reservoirs. In order to understand the dynamic reserves of shale gas reservoirs more accurately, multi-component adsorption and dissolved gas need to be considered simultaneously