In this paper, we use the tightness criterion in Besov spaces, proved by Ait Ouahra, Boufoussi and Lakhel [Stochastics Stochastics Rep. 74 (2002), 411-427] and Boufoussi, Lakhel and Dozzi [Stoch. Anal. Appl. 23 (2005), no. 4, 665-685], to give some limit theorems for occupation times problem of a sub-fractional Brownian motion. Finally, we give a strong approximation version of our limit theorems, more precisely L p -estimate version.