1. A method for updating a routing lookup tree, comprising: determining a layer update indication table and node update information according to updated entries, when determining that a routing lookup tree needs to be updated; and selecting in sequence a layer from the routing lookup tree as a current layer according to levels of layers, and if determining that the current layer needs to be updated according to the layer update indication table, then locking a previous layer of the current layer in the routing lookup tree, synchronizing the node update information to the current layer in the routing lookup tree, and so on, until determining that the current layer is a last layer needing to be updated according to the layer update indication table, and then ending the update of the routing lookup tree.