Algeria has experienced outbreaks related to mosquitoes; additionally, it is exposed at the present to the installation of the invasive species Aedes albopictus (Theobald 1907). In this context, we performed a mosquito inventory in the Algerian high plains (Setif region) from 2016 to 2018, in order to provide the list of mosquitoes in the study area and analyze their biodiversity, density and species distribution across two climate zones (Mediterranean Csa and steppe BSk Zones) using biostatistical tests. The identification of species was done using a combination of morphological and molecular approaches (COI barcoding). The sampling yielded the identification of nine mosquito species including the malaria vectors Anopheles labranchiae (Falleroni 1926) and Anopheles cinereus hispaniola (Theobald 1901). A new species Culex simpsoni (Theobald 1905) is also recorded. The COI sequences of six species are provided in Genbank (MK047302-MK047315). From the total sampled mosquitoes, Culex pipiens s.l (Linnaeus 1758) showed the highest density in BSk zone (34.7±8.9), while Culiseta longiareolata (Macquart 1838) showed the highest density (51.2±28.5) in Csa. Further, we have revealed a high and positive correlation between Culex theileri (Theobald 1903) and An labranchiae (rs=0.89, p>0.001). Moreover, the pairwise comparison and Ordination Corresponding Analyses ascertained the presence of a significant association between species distribution/density and climate zones in the study area (K-W U=51, p>0.01), and confirm the effect of the climate changes on the mosquito population. The results provided will hopefully accentuate our knowledge about mosquito population dynamics and facilitate the installation of an effective control program.