Suicide has been an important topic in recent years, but no previous studies have investigated suicide from the perspective of parent–child attachment and positive psychological qualities. Thus, we aimed to examine the relationship between parent–child attachment and children's suicidal ideation, as well as the mechanism involved. In total, 681 fourth-grade students from three elementary schools in Suzhou, China, were surveyed for two years. The results showed the following. (1) Mother–child attachment directly predicted suicidal ideation in children whereas father–child attachment did not. (2) Mother–child attachment indirectly predicted suicidal ideation in children via beliefs about adversity and hope, and father–child attachment indirectly predicted suicidal ideation in children via beliefs about adversity. (3) Parent–child attachment indirectly predicted suicidal ideation in children through beliefs about adversity (M1) and hope (M2) as a mediator set. Revealing the mechanisms associated with the generation and formation of suicidal ideation in children can help prevent possible future suicidal behaviors in children.