The previous research revealed some functional coupling among nodes in model of motor control in human brain, which described nondirectional synchronous actions among these nodes during movement-readiness state. However, causal relationships among these nodes, which represent some directional interactions in movement-readiness state, are still lack. In the present study, we used functional magnetic resonance imaging (fMRI) and conditional Granger causality (CGC) method to investigate the interactions in model of motor control in left hand’s movement readiness state. Our results showed that upper precuneus (UPCU) and cingulated motor area (CMA) revealed net causal influences with contra lateral supplementary motor areas and contra lateral caudate nucleus during the left hand’s movement-readiness state. The net causal flows among these nodes can construct a closed circuit, which is similar as the circuit found in monkey’s brain and in human’s brain in right hand’s movement readiness state. This confirmed that there was an intrinsic circuit for motor control in either right hand’s or left hand’s movement readiness. Moreover, the results of Out-In degrees indicated that bilateral primary sensorimotor areas revealed competitive relationship during left hand’s movement-readiness.