Abstract: The motion problems of a hanging chain pendulum, involving its solution of oscillation, eigenfrequency, properties, complex oscillations and energy distribution, are investigated. The present theoretical result is compared with the experiment and a method of determining the acceleration of gravity g is given. The g can be measured in this way with an accuracy of about 0. 01%. Two summation formula of the infinite series with respect to the zeros of J0（x） are educed.

Key words: hanging chain pendulum, Bessel function, acceleration of gravity, determination