Phyllotreta striolata is a major pest of Brassica chinensis, with chemical pesticides being the primary method for pest control. However, their negative impact on crop growth and environmental risks have prompted the search for low-toxicity, environmentally friendly alternatives. This study systematically evaluates the control effectiveness of two commonly used chemical pesticides, Zu Jia® and Jie Tiao®, along with their impact on the growth characteristics of B. chinensis and compares them to the biopesticide Bacillus thuringiensis (Bt) strain G033A. The control efficacy was assessed by measuring the insect population reduction rate and plant physiological indicators (weight, plant height, chlorophyll content, and root length). The differences between biopesticide and the two chemical pesticide treatments were analyzed. The results indicated that both Bt strain G033A and the chemical pesticides significantly controlled P. striolata. However, chemical pesticides (Zu Jia® and Jie Tiao®) significantly reduced the chlorophyll content, plant height, and weight of B. chinensis (p < 0.05), whereas Bt strain G033A had no significant adverse effects on these plant traits (p > 0.05). The colonization characteristics of the Bt strain suggest potential for sustained pest control, while chemical pesticides exhibited rapid pest suppression effects. The findings highlight a novel IPM strategy that integrates the long-lasting efficacy of Bt biopesticides with the rapid action of chemical pesticides, offering a more sustainable and balanced approach to P. striolata management in B. chinensis cultivation.