Oil spillage can cause harmful risks to marine ecology in a short time period and may lead to devastating long-term impacts. Meanwhile, the trends of a pH decrease due to ocean acidification deteriorate spillages’ impact. This study evaluated the influence of pH on crude oil water accommodated fraction (WAF) toxicity to the whiteleg shrimp, Litopenaeus vannamei. Post larvae of the shrimps were exposed to the crude oil-WAF with concentrations of 0%, 25%, 50%, 75%, and 100% under pH concentrations of 6.5 and 8.5 for 72 hours to quantify their mortality. The polycyclic aromatic hydrocarbons (PAHs) of the WAF were analyzed using the GC-MS method, while the LC50 was determined using probit analysis. L. vannamei showed impaired swimming ability, loss of balance, comatose, and even death when the shrimp were acutely exposed to the crude oil WAF. The 72-h LC50 were slightly lower in pH 6.5 than that of 8.5 (101.7±9.6 mL L-1 and 114.67±11.7 mL L-1 respectively). There were 14 PAH compounds presented in the crude oil-WAF in which carcinogenic compound, benzo [a] pyrene, represented 25% of the total concentration of PAHs. The interaction among PAHs may lead synergistic effects that could increase the mortality of the shrimps. However, based on the US EPA’s LC50 scale, the crude oil-WAF is still practically non-toxic to the whiteleg shrimp, L. vannamei.