This paper aims to explore the application in the combination of interior design and smart homes and constructs an intelligent algorithm of BIM+4D technology by analyzing BIM technology and its application in interior home design. The mathematical relationship of design duration is established on the basis of BIM+4D. Studied the system of BIM+ in interior home design and set up the standard and template of the interior home. The BIM+4D technology intelligent algorithm is used to analyze the survey data and verify the feasibility and development of BIM technology in the combination of interior design and smart homes. The result data shows that the amount of investment in smart home functions is increasing year by year, among which the amount of investment in smart home appliances has been at the forefront. Among the smart home functions, smart home appliances account for the highest percentage, accounting for 80; smart temperature control accounts for 50%, and smart audio accounts for 40%. Home Design VR and AR input amount growth rates of 10%, 20%, 40%, 50%, and 40%, respectively. The research in this paper is beneficial to promote better integration of interior design and smart homes.