The combustible and explosive characteristics of corn starch dust pose a significant safety risk in its production and processing. To reveal the influence of obstacle opening sizes on the flame propagation characteristics, a self-designed vertical experimental platform of a dust combustion pipeline was implemented. Specifically, the flame temperature and pressure changes in the pipeline were collected by micro-thermocouples and pressure sensors, and dust flame images under different conditions were recorded by a high-speed photography system. The results demonstrate that, after being set in the pipeline, the obstacle destroys the flame structure and causes the flame to exist in a strong turbulent and irregular state. Meanwhile, owing to the blocking of the obstacle, the flame may disappear under certain conditions and brightness is reduced. The obstacles have an incentive effect on the flame temperature, and the obstacle opening size is inversely proportional to the peak temperature of the corn dust flame. With an increasing obstacle opening size, the combustion pressure first increases and then decreases. At an opening size of 50 x 50 mm(2), the combustion pressure reaches its highest value. Although the obstacles exert an incentive increase on the combustion pressure wave at large opening sizes, obstacles with a sufficiently small opening size significantly inhibit the pressure wave propagation.