Low silicon aluminum ratio X molecular sieve (LSX) modified by lithium is widely used in the field of pressure swing adsorption (PSA) due to its high N2 adsorption capacity and nitrogen-to-oxygen separation ratio. However, the price of raw materials for the LSX synthesis increases, resulting in a higher production cost. Potassium feldspar (i.e., KAlSi3O8) is rich in aluminum oxide and silicon oxide, and potassium can also be used as a structural guide agent for LSX as an ideal raw material that can greatly reduce the production cost for the LSX synthesis. LSX was synthesized by using seed crystal as a guiding agent with a potassium feldspar from Songxian, China as a raw material, which was firstly calcined and activated at a high temperature. The effects of silicon aluminum ratio (n(SiO2/n(Al2O3)), alkali silicon ratio (n(Na2O+K2O)/n(SiO2), water alkali ratio (n(H2O)/n(Na2O+K2O)), amount of seed guide agent (ωSDA), crystallization temperature (Tcry), and crystallization time (tcry) on the structure and properties of samples were investigated. The results show that when n(SiO2)/n(Al2O3)=2.1-2.2, n(Na2O+K2O)/n(SiO2)=2.0-2.2, n(H2O)/n(Na2O+K2O)= 35-40, ωSDA=3%-5%, Tcry=90-100 ℃, tcry=10-14 h, the obtained LSX molecular sieve has a high crystallinity, and a uniform morphology, and the exchange degree of Li+ can reach 98.7%, which obtain the properties for nitrogen and oxygen adsorption separation in industry.