Traditional drug-delivery methods are limited by low bioavailability and nonspecific drug distribution, resulting in poor therapeutic efficacy and potential risks of toxicity. Mesoporous silica nanoparticles (MSNs) have attracted wide attention as drug-delivery carriers due to their large specific surface area, adjustable pore size, good mechanical strength, good biocompatibility, and rich hydroxyl groups on their surface. In this paper, MSNs were synthesized by a template method, and the morphology and pore structure were regulated. The obtained particles possessed a narrow particle size distribution and good sphericity with a diameter of 878 nm, and their growth process was consistent with the La-Mer growth mechanism. Furthermore, MSNs were modified with amino acids and loaded with rosmarinic acid (RosA), accompanied by the "outer packaging" of pectin to obtain RosA@MSNs-Pec. RosA was added at 200, 150, and 100 mg within 72 h, with a drug loading of 193, 175.5, and 156 mg/g and an encapsulation rate of 19.3, 17.6, and 15.6, respectively. Interestingly, RosA@MSNs-Pec demonstrated the dual pH and pectinase response property, and its release curve conformed to the Higuchi model, indicating that its drug-controlled release was based on Fick's law.