A set-top box, a client, a system and method for virtual desktop access are disclosed. The set-top box includes a virtual desktop access module and a network connection module. The virtual desktop access module is configured to trigger the network connection module after receiving a virtual desktop access trigger signal, and trigger a signal display operation after receiving a virtual desktop signal sent by the network connection module. The network connection module is configured to send a virtual desktop connection request message through a network after receiving the trigger signal from the virtual desktop access module, and receive the virtual desktop signal through the network and send the virtual desktop signal to the virtual desktop access module. The virtual desktop access is completed by the set-top box.