Abstract: As one of areas for hydrocarbon exploration, forelands have petroleum geological conditions for hydrocarbon enrichment and accumulation. They are the most practical areas for "secondary hydrocarbon-generation", "secondary pool-formation" and "a second time adjustment and late-stage pool-formation", and they are also the most favorable areas for "rapid pool-formation" and "many times adjustment and recent pool-formation". The tectonic styles of forelands are varied. There exist certain mutual controlling and restricting relations between the enrichment and accumulation of hydrocarbon with different tectonic styles and petroleum geologicl factors. The mixed "compressional-strike slip" tectonic style is more favorable to hydrocarbon enrichment and the formation of large oil and gas fields accumulating in late (or recent)stages. On the other hand, the tilted tectonic style in long-term uplifting areas is more favorable to the preservation of "early (primary) stage oil and gas pools".