A route computation method and system, and a path computation element (PCE) are provided. In particular, the method includes: receiving, by a bottom-level PCE which manages a routing domain including a destination node, a path computation command, performing a route computation on the routing domain managed by the bottom-level PCE, obtaining a path segment set with a destination node serving as an endpoint, and sending the obtained path segment set to an upper-level PCE of the bottom-level PCE, sending, by the upper-level PCE receiving the path segment set sent by a first lower-level PCE, the path computation command to a second lower-level PCE, receiving path segment sets sent by all lower-level PCEs, and combining and sending all the received path segment sets to an upper-level PCE of the upper-level PCE, until a top-level PCE receives path segment sets sent by all lower-level PCEs of the top-level PCE; and combining, by the top-level PCE, all the received path segment sets to generate a set of paths between the destination node and the source node.