A method for checking health of a link, comprising: receiving and saving, by a load balancer, control information generated by a keep-alive program, wherein the control information comprises a source Internet Protocol IP address, a source port, a destination IP address, a destination port, an IP address of a server to be checked, and mode information, wherein the mode information comprises a Direct Routing DR mode or a Tunnel TUN mode; performing, by a load balancer, a matching on a message received from a client according to the control information, processing the message if the matching is successful, and sending the message processed to the server to be checked; and determining, by a load balancer, that a link corresponding the server to be checked is healthy if a response message is received from the server to be checked, and determining that the link is unhealthy if no response message is received from the server to be checked; wherein performing, by a load balancer, a matching on a message received according to the control information comprises: determining whether the matching is successful by determining whether the source IP address, the source port, the destination IP address, and the destination port in the control information are respectively identical with a source IP address, a source port, a destination IP address, and a destination port in the message received; and processing the message comprises: if the mode information is determined as the DR mode, amending a destination MAC address of the message to a MAC address of the server to be checked; and if the mode information is determined as the TUN mode, adding a TUNNEL head before the destination IP address of the message. receiving and saving, by a load balancer, control information generated by a keep-alive program, wherein the control information comprises a source Internet Protocol IP address, a source port, a destination IP address, a destination port, an IP address of a server to be checked, and mode information, wherein the mode information comprises a Direct Routing DR mode or a Tunnel TUN mode; performing, by a load balancer, a matching on a message received from a client according to the control information, processing the message if the matching is successful, and sending the message processed to the server to be checked; and determining, by a load balancer, that a link corresponding the server to be checked is healthy if a response message is received from the server to be checked, and determining that the link is unhealthy if no response message is received from the server to be checked; wherein performing, by a load balancer, a matching on a message received according to the control information comprises: determining whether the matching is successful by determining whether the source IP address, the source port, the destination IP address, and the destination port in the control information are respectively identical with a source IP address, a source port, a destination IP address, and a destination port in the message received; and processing the message comprises: if the mode information is determined as the DR mode, amending a destination MAC address of the message to a MAC address of the server to be checked; and if the mode information is determined as the TUN mode, adding a TUNNEL head before the destination IP address of the message. determining whether the matching is successful by determining whether the source IP address, the source port, the destination IP address, and the destination port in the control information are respectively identical with a source IP address, a source port, a destination IP address, and a destination port in the message received; and processing the message comprises: if the mode information is determined as the DR mode, amending a destination MAC address of the message to a MAC address of the server to be checked; and if the mode information is determined as the TUN mode, adding a TUNNEL head before the destination IP address of the message. if the mode information is determined as the DR mode, amending a destination MAC address of the message to a MAC address of the server to be checked; and if the mode information is determined as the TUN mode, adding a TUNNEL head before the destination IP address of the message.