Cleaning up zombie firms is an important starting point for supply-side reform and capacity-removal policies, and it is highly valued by the central government. In recent years, as the downward pressure on Chinese economy has increased, the problem of abundant zombie firms in the economy has become prominent. There are three main issues about zombie firms that will be harmful to the economy: First, they have no economic benefits but consume a lot of resources, which makes resources unable to flow to higher-return departments and significantly reduce resource allocation efficiency. Second, they have no competitive strength but disrupt the market order, and they may cause overcapacity and insufficient research and development, encumber development in new technologies in industries, and expell excellent firms from the market. Third, insolvent as they are, they still absorb large amounts of credit resources, resulting in a shortage of funds and an increase in credit costs. However, little research has focused on the harmfulness of zombie firms to information transparency, information quality, and their impact on the information environment.　　Taking the A-share listed companies in Shanghai and Shenzhen from 2003 to 2016 as research examples, this paper empirically examines the information transparency of zombie firms. We find that zombie firms have lower information transparency and poorer information quality. More importantly, the information transparency of zombie firms has an contagion （spillover） effect. The higher the density of provincial zombie firms is, the lower information transparency of an worsen overall information environment non-zombie firms will show. However, our conclusions may raise concern about endogenous problems. We solve these problems by analyzing at the individual firm level and the provincial level respectively. At the firm level, this paper uses Propensity Score Matching （PSM） to solve the " treatment effect” problem of information transparency of zombie firms. The PSM method of this paper satisfies the common support hypothesis and conducts a balance test to ensure the robustness of regression results. In addition, this paper constructs a tool variable estimating with two-stage least squares （2SLS） to solve the endogeneity problem caused by unobserved missing variables or reverse causality. At the provincial level, there may also be endogenous problems caused by unobservable missing variables or reverse causality. This paper constructs a tool variable, which is also estimated by two-stage least squares （2SLS） to alleviate such endogenous problems.　　This paper further analyzes the mechanism and finds that when the pressure of official economic assessment is greater and the degree of product market competition is higher, the contagion （spillover） effect of information transparency of zombie firms will be further strengthened. The expansion test shows that non-zombie firms to improve information transparency can not significantly reduce the cost of debt, resulting in insufficient supply of high-quality information. In addition, the contagion effect of information transparency of zombie firms exists in both private firms and state-owned firms, reflecting the universality of harm. This paper reveals the harmfulness and contagiousness of zombie firms from the perspective of information. Problems related to zombie firms worth more attention from the government, and market-oriented policies should be explored and implemented to deal with zombie firms, in order to improve the information environment and the efficiency of resource allocation of the whole market.