In recent years, more and more nucleic acid based molecular biotechnologies were established and applied in the disease diagnosis, health evaluation, epidemiological surveillance, genetic breeding, environmental analysis, and other aspects of aquaculture. Good quality and high quantity of nucleic acid to be preserved and extracted from the samples are the prerequisites of these technologies. Sample collection and preservation methods are the key elements to ensure the successful application of the technologies. Currently, most studies use fresh material or ultra-low temperature preserved sample for RNA extraction. However, these methods are very difficult to be applied to aquatic animals, especially for field-collected samples. This study aimed to find a convenient and effective preservation solution for field-collection. Muscle tissues were taken from Litopenaeus vannamei and preserved in the ammonium solutions at different saturation and different pH at 28 ℃ for different time periods. Comparison of the RNA extraction showed that preservation solution of saturated ammonium sulfate and saturated ammonium acetate had good effect. The saturated ammonium acetate at pH 6.0 (A3) and the saturated ammonium sulfate at pH 5.2 (S3) with 25mmol/L sodium citrate and 20mmol/L ethylene diamine tetraacetic acid(EDTA) had a significant effect on tissue preservation, by comparing gene copy number by total RNA extraction, gel electrophoresis, and RT-PCR. We successfully extracted a large amount of genomic RNA, and quantitative results showed that the 18S rRNA copy number reached 105 for per milligram tissue after 4 weeks preservation in A3 and S3, while the negative control 18S rRNA copy number was 103 per milligram tissue. Preservation solutions can effectively inhibit the degradation of nucleic acid and maintain the tissue structure and cell integrity. This simple and effective preservation solution has a great significance for sample preservation, field specimen collection and subsequent molecular experiments.