The kitchen serves as a critical environment for daily domestic activities, where its design significantly impacts users' physical load and cognitive state. Traditional ergonomic evaluation methods predominantly rely on subjective reports, falling short of comprehensively capturing real-time physiological and kinematic responses during task execution. To address this limitation, this study proposes and validates a multimodal ergonomic evaluation framework that synchronously integrates surface electromyography (sEMG), galvanic skin response (GSR), electrocardiography (ECG), and an inertial motion capture system to holistically assess users' physical and mental states during typical kitchen tasks. Employing a within-subjects design, the research compared the effects of a standardized kitchen configuration versus a personalized ergonomic configuration on muscle activation, psychophysiological responses, and kinematic metrics during chopping and cooking tasks. The results demonstrated that the personalized configuration significantly reduced muscle activation intensity (e.g., ~30.5% decrease in RMS value for the anterior deltoid), alleviated psychological stress (e.g., ~29.1% reduction in skin conductance level), and improved joint angles and movement smoothness. By fusing multi-source data, this framework provides a comprehensive characterization of user state, offers reliable, objective evidence for ergonomic design and optimization, and is applicable to evaluation needs in other domestic and industrial contexts.