This invention provides a locking device sustaining high pressure in a coffee maker which comprises a brew head assembly which comprises: a slide assembly, a sealing assembly and a pop-up and roll-back assembly, operatively linked to sustain pressure up to four (4) bars. Furthermore, this invention provides a method for one-hand operation on the locking of a coffee maker comprising steps of: a) Using one hand to put the lever forward to release the lock which is controlled by two parts, the slider and the three mounts on the brew base wherein the back-and-forth movement of the slider will produce the action of locking and releasing; b) Moving the lever forward, produce the push rod that is assembled on the slider will push the slider forward so the brew head is released; c) Putting back the lever, the push rod will put back the slider so the brew head is locked; and d) after releasing the lock, the lift platform will pop up by the lift platform spring and the lid mount roll up by the hinge spring.