A high voltage device with constant current source and the manufacturing method thereof. The device includes a P type silicon substrate (1), an oxide layer (6), a drain metal (2), a source metal (3), a gate metal (4), a P+substrate contact region (51), a N+drain region (52), an N+source region (53), an N−channel region (54) connecting the said N+drain region (52) and N+source region (53), and an N−drain region (92) enveloping the said N+drain region (52); the drain metal (2) fills drain through hole (82) and connects the N+drain region (52); the source metal (3) fills source through hole (83), and connects the N+source region (53) and P+substrate contact region (51); the source metal (3) and gate metal (4) are electrically connected by connecting metal (34). The manufacturing method includes steps of forming N+drain region, N+source region, N−drain region, P+substrate contact region, N−drain region and metal layer.