The invention relates to the technical field of block chains, in particular to a block chain local account book
data synchronization method and
system. Comprising the following steps: S1, when block checking is carried out on a block chain, storing the positions of checked blocks every time checking is completed, marking the positions as two check points, and respectively writing hash values into the check points; s2, starting the
backtracking check of the new block, and when one
check point is backtracked, updating the other
check point as the mark of the position of the new block; s3, alternately updating the two check points on the block chain; s4, when the block chain is not bifurcated, the two check points are alternately updated; s5, when the block chain is bifurcated, one
check point is located in an effective bifurcated chain, and the two check points are updated alternately; and S6, when the block chain is bifurcated and one check point is located in an invalid bifurcated chain, generating a new check point by taking the check point of the main chain as a
backtracking end point, and continuously and alternately updating. The front check point and the rear check point are set in the block chain, so that the repeated
workload of checking the local account book can be reduced.