The Mastouma base is one of the last major army strongholds in a province controlled by a range of insurgent groups including al-Qaida's Syrian wing, the Nusra Front, and the Islamist Ahrar al-Sham movement.
Army units "inflicted great losses" on armed groups in battles to the north and around Mastouma, Syrian state television reported, citing a military source.
The British-based Syrian Observatory for Human Rights said most of the troops positioned in Idlib city were now in Mastouma after insurgents took over the provincial capital in March. The base is used for launching air raids in the province.
There were reports of casualties in the battles, it said, without giving details.