<p>Despite the growing prominence of livestreaming, the influence of streamer postures on sales performance remains underexplored. Grounded in mental imagery theory, this study examines how the richness and intensity of streamer postures affect sales performance. Utilizing a novel dataset of approximately 5,223,701 frames from 423 livestreaming videos across eight industry categories on a leading livestreaming platform, this study employs deep learning techniques to extract posture characteristics. An econometric model is then applied to evaluate their impact on sales performance. The results indicate that both the richness and intensity of streamer postures positively drive sales performance, with these effects further enhanced by a higher proportion of descriptive speech acts by the streamer. These findings offer practical implications for livestreaming platforms, brand companies, and streamers aiming to improve promotional strategies targeted at micro and small enterprise resellers.</p>