Under a condition of the abnormal high geothermal field, the organic petrologic characteristics of the sedimentary organic matters in the process of secondary hydrocarbon generation were brought to light with the both nature and artificial maturity sample series. This analysis indicated that the macerals and maceral groups of the sedimentary organic matters of secondary hydrocarbon generation might be different from that of the continuous hydrocarbon generation. Except for the common macerals, the thermal macerals and the thermal secondary macerals were found, which were special type macerals of the sedimentary organic matters of secondary hydrocarbon generation. The thermal macerals kept the original structure, but appeared optical anisotropy. They could be divided into three groups: thermal vitrinite, thermal exinite and thermal inertinite groups. The structure of the thermal secondary maceral was different from that forming in the period of peatification. They appeared a strongly optical anisotropy, similar to the thermal exinite. The organic petrologic characteristics of secondary hydrocarbon generation from the sedimentary organic matters were nearly correlation with their initial maturity. Based on the initial maturity, the formation cause, the optical and the structure characteristic of the macerals, the macerals and the maceral groups of secondary hydrocarbon generation from the sedimentary organic matters in the conditions of the abnormal high geothermal field were classified. The interphase forming and development might be a key factor of the thermal secondary macerals formation.