Abstract: 160 source rock samples taken from 48 wells in the Jiyang Depression are systematically studied using transmitted and reflected fluorescent lights. Amorphous solids discovered in kerogens may derive from three different types of precursors, i.e. lower planktonic astogenetic algae, cutinites of higher plants and herbaceous plants, which can have certain hydrocarbon potential and provide new evidences for the classification of kerogen types. This paper also focuses on the degradative evolution of lower planktonic algae into amorphous solids and suggests that microbial degradation prevails over algae during undermaturation, generating crude oil of low maturity; while matured oil generates during the maturation stage dominated by thermal degradation.