When I put on my new battery in my honda accord 94 lx coupe, the alarm activates when I plug negative cable

Aftermarket security system? If not, check your Owner's Manual. It can be a hidden fuse or relay. Sometimes, you can hook up the battery, close the hood, and close and lock all doors. Then, unlock the driver's door and wait 30 seconds; afterwards, open the door and the alarm system should be reset.