This study aims to measure the effect of Foreign Direct Investment(FDI)on the Gross Domestic Product(GDP)of Algeria during the period(1990-2018),by relying on the multiple regression model using regular least squares through the IBM SPSS statistics20program and others tests of time series data by using STATA such as Unit Root Test and Cointegration Test.Data were collected from the World Bank and the Algerian national bureau of statistics to show the effect of the influx of Foreign Direct Investment,Exchange Rates,Interest Rates,and the Population on the Gross Domestic Product.The findings of the study revealed that the time series values for all variables are unstable in their level,but they are stable at the first differences,which means that they are integrated from the first degree during1990-2018.Also,there is the possibility of a relationship between these variables in the long run.The coefficient value of DLFDI is-0.001and its p-value is0.935implying that a unit increase in DLFDI will decrease DLGDP with the value of0.001which is non-significant.the coefficient value of DEXR was-0.008,and its p-value is0.000implying that a unit increase in DEXR will decrease DLGDP with the value of0.008,signifying that Exchange rate is negative and significant to Gross Domestic Product.the coefficient value of DINT was-0.001and its p-value is0.031implying that a unit increase in DINT will decrease DLGDP with the value of0.003,signifying that Interest Rates is negative and significant to Gross Domestic Product.DLPOP coefficient value is-0.851with a p-value of0.322implying that a unit increase in population will decrease gross domestic product with the value of0.851which is non-significant.So this study recommends the need to encourage Foreign Direct Investment in Algeria,especially with regard to the flexibility of the legislative side and to encourage foreign direct investment in other sectors,like the tourism sector,renewable energies,and agriculture,for the advantages that Algeria has.