Captial market plays an important role in economy, and is known as an economy health index. Therefore it is essential to study this market and its decision making basis especially in Iran. Financial statements in general and general statement in particular are the key factors of decision making in this market. Income statement shows the net income of a financial period. It is also the principal basis for decision making, evaluation model, and stock princing. Its precision, accuracy, reliability and predictability have a direct relationship with decision making precision. But weakness in income measurement process as well as employing weak accounting procedures, estimations, predictions and smoothing threaten decision making role of income statement. Analysis of earning quality, in academic literature, is one of the important procedures for decreasing the above-mentioned threat. There is no perfect definition for earning quality. But risk reduction is directly related to cash realization, solvency, conservatism, precision of measurement and predictions, predictability, normal consistency, and persistence of reported income. This survey analyzing all of the earning quality indices indicated by other researchers and found that, there is a significant relationship between indices of gross profit, sales management expenses, return on capital employed and cash realization with stock returesn. But according to the research results, no significant relationship was observed between indices of receivabel accounts, accruals, productive asset reinvestment ratio, un-operational income, conservatism, operating cash flow, EPS to PEPS ratio, and inventory with stock returns.