The neutral theory of molecular evolution suggests that the accumulation of neutral mutations in the genome plays a vital role in evolutions. The genetic representation of gene expression programming (GEP), an artificial genotype and phenotype system, permits the existence of non-coding regions in the genome where neutral mutations can be accumulated. The authors introduce a concept named nave gene expression programming (NGEP) and analyze the effect in terms of neutral regions. NGEP uses the complete tree decoding method that causes more neutral regions than GEP. In order to explore the role of the genetic neutrality in NGEP, this paper makes the following contributions: 1)perfect the concept of nave gene expression programming, whose decoding method is based on complete tree; 2)analyze the characteristic of neutral regions in GEP and NGEP, and point out that NGEP has more free neutrality regions; 3)study and compare the specific role of genetic neutrality for both GEP and NGEP by controlling and adjusting the length and the number of genes and these non-coding regions, and tests the efficiency of NGEP; and 4)extensive experiments and comparisons show that NGEP is more efficient than traditional GEP in the case of similar gene redundancy, in particular, the success rate of NGEP does not change drastically with the growth of genetic neutrality.