A method for load estimation and gravity compensation on a robotic arm including a joint is provided, and includes: receiving a first torque signal and a first joint angle when the arm is at a first position and subjected to a current load; generating a first torque value, correction parameters, and no-load and maximum-load torque values; changing the load applied to the arm to an unknown load; receiving a second torque signal and generating a second torque value; estimating an estimated load value of the unknown load; moving the arm to a second position; receiving a second joint angle; and generating a compensating torque value and outputting the compensating torque value to a driver module of the arm.