This study aims to investigate the key scientific and technical issues in the construction and thermal-triggered release of ammonium persulfate (APS)-entrapped nanocapsule breaker to precisely control the chemical breaking and degradation reaction between APS and polymers in a volume fracturing project of tight oil. The research focuses on studying the mechanism of hydrophobic polymers’ nano-precipitation on the interface of water-in-oil microemulsion droplets to construct the APS-entrapped nanocapsule breaker with sizes ranging from 215 to 355 nm. The polymers are motivated to precipitate onto the droplet which easily causes a polymer shell formation with low energy-consuming. The mechanism of pre-loaded Pluronic P-123 on the shell of the nanocapsules as “thermal switches” which can be triggered by environmental temperature is comprehensively investigated. Controlled-release behaviors of the APS nanocapsule breaker under different conditions via these switches have been studied. The APS nanocapsule can delay the degradation time of HPAM up to 24 hours. The research results provide a new way to solve the degradation problem of slickwater residual in complex network systems of tight oil, especially in the deep micron-sized fracture system.