A Simulator and a simulating method for running a guest program in a host are disclosed. The simulator includes: an initialization device configured for setting content of a hypervisor page table in the host, the hypervisor page table mapping a guest physical address space to a host physical address space. The simulator further includes a binary translation device configured for employing a program logical address to perform a memory access in code translation. The simulator also includes a miss handling device configured for updating a guest translation look-aside buffer by treating a miss in a host translation look-aside buffer caused by the execution of the translated code as a miss in the guest translation look-aside buffer, wherein the host translation look-aside buffer is configured to buffer entries for mapping addresses in a guest program logical address space to addresses in the guest physical address space. The simulator further includes an update tracing device configured for, in response to the update to the guest translation look-aside buffer, perform the update to the host translation look-aside buffer. Also disclosed is a method for running a guest program in a host.