We report the realization of closed-loop operation of an optical lattice clock based on 171 Yb atoms.We interrogate the 1So →3po dock transition using single Rabi pulses of 578nm laser light.The two π-transitions from mF =± 1 /2 ground states are alteatively interrogated,and the clock laser frequency is locked to the center of the two resonances.The in-loop error signal stability of the clock reaches 3 x 10-17 for an average time of 3500s.We also perform interleaved operations of the clock with two independent servo loops,and the fractional frequency difference averages down to 2 × 10-16 in 7200s.