In order to clarify the ionic regulation methodology for shrimp farming with inland saline waters, a feeding trial was conducted to investigate the effects and mechanism of ambient Mg²⁺ and Ca²⁺ concentrations on the growth and energy budget of juvenile Litopenaeus vannamei using artificial seawater at salinity 30. Eight treatments were set: R1, R2, R3, R4, R5, R6, R7 and R8, and the Mg²⁺/Ca²⁺ ratios and Mg²⁺,Ca²⁺ concentrations (mg/L) were 0.11(35, 330), 0.53(175, 330), 1.59(525, 330), 2.42(800, 330), 3.36(1110, 330), 4.78(1110, 232), 7.87(1110, 141) and 11.81(1110, 94), respectively. The experiment lasted 40 days, but Treatment R8 just continued for 30 days because of shrimp mortality. During the experiment, the growth, molting, food conversion efficiency and energy budget of L. vannamei were all significantly affected by both Mg²⁺and Ca²⁺ concentrations in the water (P<0.05). However, shrimp food consumption was just significantly influenced by Ca²⁺ concentration (P<0.05), not by Mg²⁺. It indicated that L. vannamei had powerful ability to endure very low ambient Mg²⁺ concentration, but it was vulnerable to low Ca²⁺ concentration. In conclusion, if using Mg²⁺ or Ca²⁺ deficient saline groundwater for shrimp farming, we only need to complement the Mg²⁺ concentration to at least 15% of its normal level or Ca²⁺ concentration to 60% of its normal level in seawater by adding magnesium or calcium salt, and the shrimp growth could be normal.