A message transmission method performed by a first relay node in a blockchain relay communication network, comprising: receiving a registration request from each blockchain node in the blockchain relay communication network; respectively registering, based on the registration request submitted by the each blockchain node, the blockchain node to a blockchain node set indicated by the registration request; respectively generating a routing policy corresponding to the each blockchain node, wherein the routing policy comprises the blockchain node set to which a corresponding blockchain node pertains and a connected relay node; receiving, from a connected blockchain node, a first blockchain message sent for a target blockchain node, wherein the target blockchain node is present in a target blockchain node set; in response to receiving the first blockchain message, querying information of the blockchain node connected to the first relay node, a primary routing table and a secondary routing table, until target relay nodes on a route forwarding path between the first relay node and the target blockchain node are determined, wherein the primary routing table is configured to record routing policies corresponding to blockchain nodes respectively connected to all relay nodes in a relay node set to which the first relay node pertains, and wherein the secondary routing table is configured to record routing policies corresponding to blockchain nodes respectively connected to all relay nodes in the blockchain relay communication network or routing policies corresponding to blockchain nodes respectively connected to remaining relay nodes in the blockchain relay communication network not added to the relay node set; and transmitting the first blockchain message to the target blockchain node through the target relay nodes. receiving a registration request from each blockchain node in the blockchain relay communication network; respectively registering, based on the registration request submitted by the each blockchain node, the blockchain node to a blockchain node set indicated by the registration request; respectively generating a routing policy corresponding to the each blockchain node, wherein the routing policy comprises the blockchain node set to which a corresponding blockchain node pertains and a connected relay node; receiving, from a connected blockchain node, a first blockchain message sent for a target blockchain node, wherein the target blockchain node is present in a target blockchain node set; in response to receiving the first blockchain message, querying information of the blockchain node connected to the first relay node, a primary routing table and a secondary routing table, until target relay nodes on a route forwarding path between the first relay node and the target blockchain node are determined, wherein the primary routing table is configured to record routing policies corresponding to blockchain nodes respectively connected to all relay nodes in a relay node set to which the first relay node pertains, and wherein the secondary routing table is configured to record routing policies corresponding to blockchain nodes respectively connected to all relay nodes in the blockchain relay communication network or routing policies corresponding to blockchain nodes respectively connected to remaining relay nodes in the blockchain relay communication network not added to the relay node set; and transmitting the first blockchain message to the target blockchain node through the target relay nodes.