This research aims to generalize the conceptual basis of precariousness of employment, study the factors and scale of unsustainable of employment in the countries of the Eurasian Economic Union (EAEU). The concept of precariousness of employment is formed in social and economic studies about 40 years ago, but objective and subjective conditions and forms of unsustainable employment existed before. This study proposes a classification of forms of precariousness of employment on 16 criteria: the duration and timing of agreements, contract terms, the nature of income; the degree of labor autonomy; the level of formality; the level of openness; the level of vulnerability; the conditions of growth of qualification; the level of flexibility; the level of stability; regularity; the severity of the danger of work; in relation to the workplace; the quality of employment, the level of social security. In this research highlighted factors (globalization, demography, migration, structure factors, shadow and informal economy, social development and living standards, unemployment), and systematized certain trends of precariousness of employment, channels and means, forms of manifestation. The empirical analysis identified of the labor potential of the Eurasian countries and new quantitative estimates of the levels of unsustainable employment in the Eurasian Economic Space.