This study investigates the effects of low-intensity focused ultrasound (LIFU) on the dorsal anterior cingulate cortex (dACC) in reducing acute pain perception and altering autonomic responses. Sixteen healthy volunteers received transient contact heat pain stimuli during either LIFU to the dACC or sham stimulation. Continuous electroencephalogram (EEG), electrocardiogram (ECG), and electrodermal response (EDR) were recorded. The results showed that LIFU reduced pain ratings by 1.09 ± 0.20 points compared to sham stimulation. LIFU also increased heart rate variability indexed by the standard deviation of normal sinus beats (SDNN), low-frequency (LF) power, and the LF/HF ratio. There were no significant effects on blood pressure or EDR. LIFU resulted in a 38.1% reduction in the P2 component of the contact heat-evoked potential (CHEP). These findings suggest that LIFU to the dACC can reduce pain and alter autonomic responses to acute heat pain stimuli, providing insights into the causal role of the dACC in pain and autonomic processing.This study investigates the effects of low-intensity focused ultrasound (LIFU) on the dorsal anterior cingulate cortex (dACC) in reducing acute pain perception and altering autonomic responses. Sixteen healthy volunteers received transient contact heat pain stimuli during either LIFU to the dACC or sham stimulation. Continuous electroencephalogram (EEG), electrocardiogram (ECG), and electrodermal response (EDR) were recorded. The results showed that LIFU reduced pain ratings by 1.09 ± 0.20 points compared to sham stimulation. LIFU also increased heart rate variability indexed by the standard deviation of normal sinus beats (SDNN), low-frequency (LF) power, and the LF/HF ratio. There were no significant effects on blood pressure or EDR. LIFU resulted in a 38.1% reduction in the P2 component of the contact heat-evoked potential (CHEP). These findings suggest that LIFU to the dACC can reduce pain and alter autonomic responses to acute heat pain stimuli, providing insights into the causal role of the dACC in pain and autonomic processing.