For the analysis of cadmium, the toxicity of spectroscopic methods is increasing because the measurement of the low level for detection of this element is done in various samples. This review studies the methods of separation and pre-concentration and analyzes spectroscopic methods for detecting cadmium in water samples. Considering the amount of trace cadmium ion in the analysis of aqueous samples, a suitable method should be used. From the past, chemists have been trying to find a solid phase to recover analytes from the water matrix. The experimental method of SPE is a standard method for the analysis of heavy metals such as cadmium ion in aqueous samples. Cadmium is known worldwide as a toxic metal. Therefore, it is often necessary to determine this element in environmental, biological, food and agricultural samples. However, analyses are difficult because the quantities of cadmium samples are relatively small, except for trace amounts. Measurements are made by flame atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry.For this reason, several preconcentration methods for the determination of cadmium ion, including solid phase extraction, coprecipitation and cloud point extraction, has been reviewed.A brief history of using Solid-phase extraction in the analysis of cadmium ion in water samples is presented in this paper.