Based on the studies of PIs in L1 text comprehension ，the present study takes the Chinese EFL learners of differ- ent English levels as the research subjects and applies naming experiment and critical-line reading experiment to explore the effect of textual causal constraint and readers ’L2 / FL proficiency level on the activating and encoding of PIs in text comprehension． To synthesize the results of two experiments ，the researchers drew the following conclusions． First ，the textual causal constraint af- fects the on-line activation of PIs in L2 / FL text reading process and readers are more likely to make PIs when the textual causal constraint is high． Second ，the activation of PIs is also affected by readers ’language proficiency in L2 / FL text reading process and advanced English proficiency readers can activate on-line PIs ，while middle-level readers can not． Third ，for advanced Eng- lish readers ，PIs can encode in their short-term memory representation after its activation ，but this encoding is only some partial encoding．