This study analyses how the old-age income security of precarious workers varies according to the type of multi-level pension system focusing on the increasing precarious workers in the post-industrial South Korea. In the service economy, precarious workers experience complex precariousness in terms of employment, income, and social wage. This study aims to compare the effect of multi-level pension systems on the relationship between the precarious work in labour market and the old-age pension benefit. Specifically, I construct four hypothetical precarious workers group representing the precariousness in the labour market in Korea and compare the benefit levels of the groups in three different pension systems. The result shows that the Partially Guaranteed pension system does not ensure the sufficient old-age pension benefit of precarious workers. However, the gap in pension income by the groups is smaller than other groups, which refers to that the pension system provides with low level of pension income not only precarious groups but stable workers. In addition, pension income of precarious worker groups in Partially Guaranteed pension system fluctuate with their experience of precarious work before retirement. In the conclusion, I suggest a possible way to reform the Korean pension system to ensure the old-age income security of precarious workers in the post-industrial labour market.