This study recruited 9,830 participants to identify whether the interaction between obesity and hypertension affects the occurrence of arteriosclerosis in Chinese adults. Brachial–ankle pulse wave velocity (baPWV) was measured to diagnose arteriosclerosis. Unconditional logistic regression was used for multiplicative interaction. The additive interaction was represented by relative excess risk due to interaction (RERI), attributable proportion (AP), and synergy (S). Hypertension was an independent risk factor for baPWV ( p < .01), but obesity was not ( p = .08). The interaction between obesity and hypertension on arteriosclerosis was not multiplicative (adjusted odds ratio = 0.89 (0.79–1.01), p = .07), but a negative additive interaction (RERI = −4.33, AP = −2.91, S = 0.10; p < .01) exists. Therefore, obesity may reduce the risk of arteriosclerosis caused by hypertension when hypertension and obesity coexist, especially in women and middle-aged people, which supports the obesity paradox.