Abstract: By No. 742 resin, a domestic product of macroporous cation exchanger, the basic nitrogen compounds, a catalyst poison, were isolated from shengli straight-run gas oil, and the analyses concerned were made. A set of rate constants and adsorption coefficients of certain nitrogen compounds on CRC-1 molecular sieve for light fuel oil cracking network has also been obtained. The respective coefficients of 2-ethyl pyridine, isoquinoline and 8-hydroxyquinoline are 45.46, 37.00 and 23.40 (g basic nitrogen/g catalyst)~(-1). But the real adsorption coefficient of the basic nitrogen compounds present is actually 42.