Anson Chi of Plano entered the plea Wednesday in federal court in Sherman, where he was indicted this month.
Chi remains in custody without bond pending trial on a charge of possession of an unregistered firearm or explosive device.
Investigators say Chi was seriously hurt June 18 when a bomb he allegedly made exploded on a natural gas regulator in Plano. Authorities say the device went off prematurely and caused little damage.
Chi's next court hearing is set for early September.