Abstract: This study presented a novel analytical strategy employing in-situ atmospheric pressure photoionization high-resolution mass spectrometry (in-situ APPI-HRMS) coupled with direct orifice sampling for the online and real-time analysis of heavy gaseous components (m/z>200) generated during the pyrolysis of Dominican cigar leaves. Traditional methods, for example, single photoionization mass spectrometry (SPI-MS), face significant challenges in detecting these heavy components due to their large molecular weight, high boiling point and unstable chemical structure. Offline methods involving condensation risk induce secondary reactions, which compromise the integrity of the initial pyrolysis products. In the present work, the experimental setup featured a pyrolysis reactor directly interfaced with an Orbitrap mass spectrometer equipped with an in-situ APPI source. Sampling was performed through a small orifice (0.5 mm in diameter) on the reactor, which was maintained at the pyrolysis temperature to minimize condensation. Pyrolysis products were immediately photoionized upon escape by a 117 nm vacuum ultraviolet (VUV) light emitted from a lamp positioned within 5 mm of the orifice and the ion transfer tube. A counter-flow of high-purity nitrogen gas prevented atmospheric interference, avoided VUV light absorption, suppressed sample oxidation, and diluted gaseous products to avert secondary oligomerization. A critical comparison between in-situ APPI-HRMS and SPI-MS for the analysis of pyrolysis products at 650 ℃ revealed the distinct superiority of APPI-HRMS in detecting heavy components. Leveraging its real-time monitoring capability, this study investigated the dynamic release profiles of heavy gaseous products at different pyrolysis temperatures (450 ℃ and 650 ℃), revealing that the peak release times of all products were advanced by approximately 15 s at elevated temperatures, with nicotine (C₁₀H₁₄N₂) being the earliest released compound. These findings provide insights into the analysis of flavor profile dynamics in cigars. Furthermore, the effect of pyrolysis temperature on the gaseous products from cigar leaf pyrolysis was systematically analyzed and discussed. The results demonstrated that pyrolysis at 650 ℃ promotes secondary reactions such as dehydrogenation and condensation, leading to the formation of compounds with higher carbon numbers (C>18) and higher double bond equivalents (DBE>10), particularly N₁-and O₃-class species. In contrast, pyrolysis at 450 ℃ primarily generates low-molecular-weight compounds with lower DBE values. In conclusion, the in-situ APPI-HRMS coupled with an orifice sampling strategy was demonstrated to be highly effective for the sensitive, real-time, and online analysis of heavy gaseous pyrolysis products from Dominican cigar leaves, thus providing a novel technical foundation for in-depth investigation in the chemical composition of heavy gaseous products during cigar leaf pyrolysis.