An assembled front housing of a treadmill includes a panel, a first side casing and a second side casing respectively laterally connected to two opposite sides of the panel for covering a drive device and a lifting device of the treadmill. The first side casing includes a first connecting portion formed thereon and the second side casing includes a second connecting portion formed thereon. The panel includes a third connecting portion and a fourth connecting portion respectively laterally extending from the two opposite sides of the panel and respectively connected to the first connecting portion of the first side casing and the second connecting portion of the second side casing.