Abstract: A dropper seatpost with double gas chambers is revealed. The dropper seatpost mainly includes a hydraulic inner tube and an outer tube in which the hydraulic inner tube is moveably mounted. A second gas chamber is formed between the hydraulic inner tube and the outer tube. While increasing a height of a saddle mounted above the hydraulic inner tube, pressure of high-pressure gas in the second gas chamber not only improves speed and fluency of the hydraulic inner tube being lifted, but also optimizes concentricity and side force resistance of both the hydraulic inner tube and the outer tube. The high-pressure gas in the second gas chamber also reduces abnormal sound produced by bubbles. Each of two ends of the outer tube is provided with a seal member for protecting the outer tube from pollutants outside. Thereby both durability and service life are improved.