Abstract: Abstract: Aiming at solving problems of large own gravity and high transportation cost as well as the more needed bearing capacity of the concrete narrow-gap slatted floor caused by improperly design of the cross section, calculation hypothesis, conversion of cross section and load were carried out to analyze the structure of the concrete narrow-gap slatted floor in this study. It can be assumed that one fattening pig weights 100 kg on average and its four legs bear equal body weight. According to the dimension of the concrete narrow-gap slatted floor and fattening pigs, maximally, 10 pig legs can appear on one concrete narrow-gap slatted floor at the same time. The real cross section of the concrete narrow-gap slatted floor was changed into "T" cross section and 10 concentrated loads which were caused by legs were converted into continuous load in the calculation process. Based on the calculation results, it was concluded that the bearing capacity of the concrete narrow-gap slatted floor was larger than that needed. Therefore, optimization of materials, shape and dimension reinforcement of the narrow-gap slatted floor and mechanical calculation were done. After the optimization, for single narrow-gap slatted floor, the grade of the concrete changed from C30 to C25, consume of concrete saved approximately 0.01 m3, area of cross section of narrow-gap slatted floor and its reinforcement bar were decreased by 3600 mm2 and 213 mm2 respectively. Under the conditions mentioned above, the normal section flexural capacity value was 3.14 kN·m, inclined section resisting shear value was 3.56 kN, crack width value was 0.167 mm, and defection of the middle section value was 3.70 mm, which all met the requirements of the code design of concrete structures. After the optimization, the material cost of single narrow-gap slatted floor was decreased by 41% and cost reduction of paving one square meter narrow-gap slatted floor was 18%. However, all the data came from the calculation and results were needed to be examined in the real test and production.