The invention discloses a method for judging a fluid type of a reservoir by utilizing logging data of while-drilling drilling fluid, which comprises the following steps of: A, data collection, i.e., collecting performance parameters of the while-drilling drilling fluid of a target stratum, wherein the performance parameters comprise electrical conductivity, a temperature, drilling time and a hydrocarbon component of the drilling fluid; B, data processing; C, setting of a crossplot graph data track, i.e., for a plumb shaft, respectively combining an Sf data track and a Tf data track to form an S-T data track, combining the Sf data track and a DHf data track to form an S-DH data track and respectively making crossplots; D, judgment of the fluid type, i.e., using the S-T dat track for judging a dry layer (a micro gas-bearing bed) and an aqueous layer, using the S-DH data track for the plumb shaft to judge the gas-bearing bed or a gas reservoir and using a DO-DH data track for judging an oil-bearing formation or the gas-bearing bed. When the method is adopted, an explanation result of the method is objective and accurate, the coincidence rate of the explanation result and the oil testing conclusion is high, and the requirements on production and research can be met.