From 32 isolates of actinomycetes isolated from poultry compost in Annaba (East Area Algeria), three autochthones strains Cpt20, Cpt8, Cpt29 screened for their ability of producing thermostable xylanase activities based on the diameter of the clear zone formation in birchwood xylan agar plates. One of them, as Actinomadura keratinilytica Cpt20 produced high amount of extracellular xylanases, this strain was selected and optimized for xylanase enzyme produced in liquid state fermentation. Consequently, for commercial applications, it is advisable to develop processes production starting from inexpensive substrates. The presence of wheat bran as a carbon source in the medium induced the highest production of xylanase (30.64IU/ml). This result is particulary valuable because the other substrates are more expensive. Among all the organic and inorganic sources of nitrogen tested in the study, peptone was found to be the best in stimulating xylanase produced by Actinomadura keratinilytica Cpt20. Optimum pH and temperature for xylanase activity were found to be 8.5 and 45°C after 72h of incubation. After optimization of various production parameters, an increase of nearly 2-fold in xylanase production was achieved. The enzyme has an optimal temperature at 70°C and the half-life of the xylanase at 75°C was 30min.