Modern IC designs often involve outsourced IP cores. It is convinced that there are opportunities in which the IP cores contain malicious logic, namely hardware Trojan (HT), which raises serious concerns about the trustworthiness of ICs used in mission-critical applications. This paper proposes an HT detection method by analyzing the combined structural features of HTs and host circuits. The structural features of combinational and sequential logic HTs are extracted and form an HT feature database. An efficient quantization approach on feature matching is proposed to search the features from circuit designs. The experiments conducted on TrustHub benchmarks show that the proposed method can successfully detect all stealth Trojans with runtime within 72 s on a platform with an AMD 2.00-GHz CPU with 4-GB RAM and a low false positive rate compared with the existing methods. INDEX TERMS Structure features, hardware Trojan, gate-level circuits.