Seasonal variation in the physiological indices and biochemical composition of the sea urchin Paracentrotus lividus (Lamarck, 1816) (Echinodermata Echinoidea) from the west coast of Algeria were studied between March 2016 and February 2017 from three stations of different nature and geographical position: Sidi Lakhdar (S1), Cap Carbon (S2), and Benisaf harbor (S3). Two spawning period occurred in spring and autumn, resulting in a fall in gonad indices to a low level with values between 2.14 and 3.65%. The seawater temperature in the three sampling stations revealed that the latter had a spawning rate at 9-15 °C in spring and 24 and 11 °C in autumn corresponding to the two peaks of spawning. The biochemical composition of the gonads protein contents, carbohydrates and lipids were recorded with a high percentage for proteins between (25.80 and 45.23%) followed by that of lipids (9.21 and 14.40%) and finally carbohydrates (3.49 and 7.39%). In accordance with the gonad cycle, sea urchin lipids and proteins show a marked seasonal variation with a decrease in their percentages during the spawning period. Protein levels had an inverse profile with carbohydrates, with their values at a minimum when carbohydrates were at their maximum. The profile of the total components in the gut content is almost the same as in the gonads with minus values. A relationship has been found between the biochemical components of the gonads and the digestive tract during gametogenesis, the latter seems to be an organ that tends to store nutrients, indicating that populations of sea urchin P. lividus are in good nutritional conditions.