The invention discloses an adjustable pitch propeller experiment apparatus in a marine propulsion apparatus, wherein the adjustable pitch propeller experiment apparatus is used for experiment teaching. A main transmission shaft of a main transmission mechanism is a hollow shaft. A front end is connected with a propeller hub and a rear end is fixedly sleeved on a second spur gear. The second spur gear simultaneously engages with a first spur gear of a load motor and a third spur gear of a driving motor. A pitch adjusting mechanism is arranged in the propeller hub and propeller hub end cap. A stepping motor of the pitch adjusting mechanism in the main transmission shaft is coaxially connected with a first transmission shaft. A first bevel gear is fixedly arranged on the first transmission shaft. The first bevel gear simultaneously engages with three second bevel gears which are arranged to form 120 DEG on a peripheral direction of the first transmission shaft. The each second bevel gearis fixedly sleeved on a lower end of a second transmission shaft. The each second transmission shaft is vertical to the first transmission shaft and an upper end of the each second transmission shaftis connected with a paddle. The main transmission mechanism and the pitch adjusting mechanism can simultaneously realize propeller rotation and pitch adjusting, and adjust the pitch and feed back a pitch angle in real time.